Bài kiểm tra môn Toán 8

Hä vµ tªn HS:................................................. Líp : 8.......... Bµi kiÓm tra M«n to¸n 8 Thêi gian 45 phót §iÓm NhËn xÐt cña gi¸o viªn I. Tr¾c nghiÖm kh¸ch quan (3,0 ®iÓm) Tõ c©u 1 ®Õn c©u 6 cã 4 ph­¬ng ¸n tr¶ lêi A, B, C, D; trong ®ã chØ cã mét ph­¬ng ¸n tr¶ lêi ®óng. H·y chän ch÷ c¸i ®øng tr­íc c©u tr¶ lêi ®óng råi viÕt vµo bµi lµm. C©u 1: KÕt qu¶ phÐp nh©n 5x2 (3x2 – 7x + 2) lµ: A. 15x4 – 7x + 10x2 B. 15x4 +35x2 + 5x2 C. 15x4 -7x + 2 D. 15x4 - 35x3 + 10x2 C©u 2: ViÕt tÝch sau: (x – 3y) (x + 3y) thµnh ®­îc kÕt qu¶ lµ: A. x2 – 9y2 B. x2 + 9xy + 9y2 C. x2 - 6xy + 9y2 D. Mét kÕt qu¶ kh¸c. C©u 3: BiÓu thøc thÝch hîp ph¶i ®iÒn vµo chç trèng ( … ) (x – 3)( …….. ) = x3 – 27, ®Ó ®­îc mét h»ng ®¼ng thøc lµ: A. x2 + 3 B. x2 + 3x +9 C. x2 – 3x + 9 D. x2 + 6x + 9 C©u 4: KÕt qu¶ cña phÐp tÝnh 20102 – 20092 lµ: A. 4019 B. 2009 C. 2010 D. 1 C©u 5: §¬n thøc – 12x2y3 kh«ng chia ®­îc cho ®¬n thøc nµo sau ®©y: A. – 2x3y2 B. – 6x2y3 C. 2x2y D. 5x2y C©u 6: §Ó ®a thøc x2- 3x + m chia hÕt cho ®a thøc x – 2 th× gi¸ trÞ cña m lµ: A. 2 B. – 2 C. – 1 D. 1 II. Tù luËn: (7 ®iÓm) Bµi 1: (3,5®) Ph©n tÝch ®a thøc sau thµnh nh©n tö : a) x (3 + x) – y(x + 3) . b) x3 – 6x2 + 12x – 8 c) x4 – 9x3 + x2 – 9x Bµi 2: (2,5®) T×m x, biÕt: a) 5x – 2x2 + 2x(x – 1) = 15 b) 3x2 – 9 = 0 Bµi 3: (1®) Chøng minh r»ng: x2 – 5x + 7 > 0 víi mäi sè thùc x . 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