Tài liệu đề khảo sát chất lượng toán 8

TRƯỜNG THCS............................. PHIẾU KHẢO SÁT CHẤT LƯỢNG Họ và tên: ......................................... Môn : Toán 8 Lớp: 8 ........ Năm học: 2012 - 2013. Đề A Thời gian: 30 phút (không kể giao đề) Điểm Chữ ký giám khảo Chữ kí CB coi thi I. PHẦN TRẮC NGHIỆM: (3 điểm) Hãy khoanh tròn đáp án mà em cho là đúng trong các câu sau: Câu 1. NÕu (2x+3)2 = 4x2+ ax + 9 th× a b»ng: A.2 B.3 C.12 D.6 3 3 2 Câu 2. NÕu (2x-3) = 8x - 36x + ax-27 th× a b»ng: A.6 B.18 C.36 D.54 2 Câu 3. KÕt qu¶ khi ph©n tÝch ®a thøc 3xy + 6xyz thµnh nh©n tö lµ: A. 3xy ( 3y + z) B. 3xy ( y + 3z) C . 3xy ( y + 2z) D. 3xy ( 2y + z) Câu 4. KÕt qu¶ khi ph©n tÝch ®a thøc 4x2-1 thµnh nh©n tö lµ: A. (2x+1)(2x-1) B. (4x-1)(2x+1) C. (2x-1)(2x-2) D. (4x-1)(2x+2) Câu 5. H×nh thang ABCD cã AB // CD ; AB = 8 cm ; CD = 10 cm , ®êng trung b×nh cña h×nh thang ABCD b»ng : A. - 9 cm B. 9 cm C. -18 cm D. 18 cm Câu 6. Cho tam gi¸c ABC cã M, N lÇn lît lµ trung ®iÓm cña AB, AC vµ BC = 6cm . Khi ®ã ®é dµi ®êng trung b×nh MN b»ng: A. 12 cm. B. 6 cm C. 3cm D.Kh«ng x¸c ®Þnh ®îc II. PHẦN TỰ LUẬN: (7 điểm) Câu 1. (2 điểm). Ph©n tÝch c¸c ®a thøc sau thµnh nh©n tö: a. 5x + 10 + x( x + 2) b. x2 + 4x - y2 + 4 ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... Câu 2. (2.5 điểm). T×m x biÕt: a) x2 + 2x + 1 = 0 b) x2 + 5x = 6 ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... Câu 3. (2.5 điểm). Cho tø gi¸c ABCD, gäi E,F,G,H lÇn lît lµ trung ®iÓm cña AB , BC, CD, vµ DA. Chøng minh r»ng EFGH lµ h×nh b×nh hµnh. ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... TRƯỜNG THCS............................. Họ và tên: ......................................... PHIẾU KHẢO SÁT CHẤT LƯỢNG Môn : Toán 8 Lớp: 8 ........ Đề B Điểm Năm học: 2012 - 2013. Thời gian: 30 phút (không kể giao đề) Chữ ký giám khảo Chữ kí CB coi thi I. PHẦN TRẮC NGHIỆM: (3 điểm) Hãy khoanh tròn đáp án mà em cho là đúng trong các câu sau: Câu 1. NÕu (2x-3)2 = 4x2- ax+9 th× a b»ng: A.-2 B. 3 C. 6 D. 12 3 3 2 Câu 2. NÕu (2x+3) = 8x + 36x + ax+27 th× a b»ng: A.-6 B. 18 C . 54 D.-36 2 Câu 3. KÕt qu¶ khi ph©n tÝch ®a thøc 3xy - 6xyz thµnh nh©n tö lµ: A. 3xy ( 3y - z) B. 3xy ( y - 3z) C . 3xy ( y - 2z) D. 3xy ( 2y - z) Câu 4. KÕt qu¶ khi ph©n tÝch ®a thøc 9x2-1 thµnh nh©n tö lµ: A. (3x-1)(3x-2) B. (9x-1)(3x+1) C. (9x-1)(9x+1) D. (3x-1)(3x+1) Câu 5. Hình thang ABCD coù AB // CD ; AB = 5 cm ; CD = 7 cm , ñöôøng trung bình cuûa hình thang ABCD baèng: A. 5 cm B. 7 cm C. 6 cm D. 12 cm Câu 6. Cho tam giác ABC có BC = 6cm . Khi đó độ dài đường trung bình MN bằng: A. 12 cm. B. 6 cm C. 3cm D.Không xác định được II. PHẦN TỰ LUẬN: (7 điểm) Câu 1. (2 điểm). Phân tích các đa thức sau thành nhân tử: a. 5y - 10 + y( y - 2) b. y2 - 4y - x2 + 4 ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... Câu 2. (2.5 điểm). Tìm y biết a) y2 - 2y + 1 = 0 b) y2 + 4y =5 ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... Câu 3. (2.5 điểm). Cho tứ giác MNPQ, gọi I,J,H,K lần lượt là trung điểm của MN, NP, PQ, và QM. Chứng minh rằng IJHK là hình bình hành. ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... ....................................................................................................................................................................................................................... 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ĐÁP ÁN- BIỂU ĐIỂM Toán 8 ĐỀ A I. PHẦN TRẮC NGHIỆM: (3 điểm) Mỗi câu trả lời đúng được 0,5 điểm C©u 1 2 3 4 5 6 §¸p ¸n C D C A B C II.Tù luËn (7 điểm). Câu 1. (2 điểm). Phân tích các đa thức sau thành nhân tử: a. 5( x + 2) + x( x + 2) (0,5®) =(x+2)(5+x) (0,5®) b. x2 + 4x - y2 + 4 = (x+2)2 - y2 (0,5®) = (x + 2 + y). (x + 2 - y) (0,5®) Câu 2. (2.5 điểm). Tìm x biết: a) a) x2 + 2x +1 = 0 (x+1)2= 0 (0,5®) x = -1(0,5®) Vậy x = -1 b) x2 + 5x = 6 x2 + 5x – 6=0 x2 –x + 6x – 6=0 (0,5®) 2 (x –x )+ (6x – 6)=0 x(x –1 )+ 6(x –1)=0 (x - 1)(x + 6) =0 (0,5®) x-1 =0 hoÆc x+6 =0 * x-1 =0  x=1 * x+6 =0 x=-6 Vậy: x =1; x = -6 (0,5®) Câu 3. (2.5 điểm). Cho tứ giác ABCD , gọi E,F,G,H lần lượt là trung điểm của AB , BC, CD, và DA. Chứng minh rằng EFGH là hình bình hành. VÏ h×nh, viÕt GT,KL (0,5®) V× : EF lµ ®êng trung b×nh cña 1 AC 2 1 T¬ng tù => GH // = AC 2 ABC => EF // = => EF //= GH (0.75 ®) (0.75 ®) (0,5®) vËy tø gi¸c EFGH lµ h×nh b×nh hµnh. ĐỀ B I. PHẦN TRẮC NGHIỆM: (3 điểm) Mỗi câu trả lời đúng được 0,5 điểm C©u 1 2 3 4 5 §¸p ¸n D C C D C II.Tù luËn (7 điểm). Tương tự đề A - Học sinh làm phương pháp khác nếu đúng vẫn cho điểm tối đa - Điểm làm tròn đến 0.5 6 D