Tài liệu De kiem tra chat luong dau nam khoi 8 pc

Hoï teân HS :________________________ Tröôøng THCS Caùi Daàu. Lôùp : _________ Giaùm thò BAØI KIEÅM TRA HOÏC KYØ II Moân toaùn : 8PC Thôøi gian 90’ Lôøi pheâ : Caâu 1 : Giaûi caùc phöông trình : a) 4(1 – 3x) – (2 – 3x) = 38 – 18x (1,5ñ) b) 3 – 4x(5 – 2x) = 8x2 - 177 (1,5ñ) c) x 1 x  3  x2 x (2ñ) Caâu 2 : Giaûi baát phöông trình : 4x  3 5x  3 1  9 6 (2ñ) Caâu 3 : (3ñ) Cho tam giaùc ABC vuoâng taïi A, coù AB = 9cm, AC = 12cm. Tia phaân giaùc cuûa goùc A caét BC taïi D. Töø D keû DE vuoâng goùc vôùi AC (E  AC). Tính ñoä daøi caùc ñoaïn thaúng BC ; BD ; CD ; DE. 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Ñaùp AÙn Caâu 1 : a)    4(1 – 3x) – (2 – 3x) = 38 – 18x 4 – 12x -2 + 3x = 38 – 18x 9x = 36 x=4 b) 3 – 4x(5 – 2x) = 8x2 - 177  3 – 20x + 8x2 = 8x2 – 177  20x = 180  x=9 c) x 1 x  3  x2 x ÑK : x  2 (0,5ñ) (0,5ñ) (0,5ñ) (0,5) (0,5) (0,5) (1) (1)  x(x -1) = (x -2)(x + 3)  x 2 – x = x2 + x – 6  2x = 6  x=3 4x  3 5x  3 1  9 6 A  2(4x +3) – 18  3(5x + 3)  8x + 6E –1218  15x + 9 9  8x – 15x  9 – 6 + 18  -7x  21 B D  x  -3 C (0,5) (0,5) (0,5) (0,5) Caâu 2 : Caâu 3 : (0,5) (0,5) (0,5) (0,5) 0,5 ñ Hình veõ 0,5 ñ Duøng Pitago tính ñöôïc BC = 15 cm BD DC BD  DC 15 5     AB AC 9  12 21 7 5 45  BD  .9  7 7 5 60 DC = .12  7 7 60 9. DE DC AB.DC 36   DE   7  AB BC BC 15 7 0,5 ñ 0,5 ñ 0,5 ñ 0,5 ñ