(1)(2x2)3﹣6x3(x3+2x2+x)(2)x(x﹣y)+(2x+y)(x﹣y)(3)(3mn+1)(3mn﹣1)﹣8m2n2(4)[(x+y)2﹣(x
题型:解答题难度:一般来源:云南省月考题
(1)(2x2)3﹣6x3(x3+2x2+x) (2)x(x﹣y)+(2x+y)(x﹣y) (3)(3mn+1)(3mn﹣1)﹣8m2n2 (4)[(x+y)2﹣(x﹣y)2]÷(2xy) |
答案
解:(1)原式=8x6﹣6x6﹣12x5﹣6x4=2x6﹣12x5﹣6x4; (2)原式=x2﹣xy+2x2﹣xy﹣y2=3x2﹣2xy﹣y2; (3)原式=9m2n2﹣1﹣8m2n2=m2n2﹣1; (4)原式=[x2+2xy+y2﹣x2+2xy﹣y2] ÷2xy=4xy÷2xy=2. |
举一反三
求值:x(x+2y)﹣(x+1)2+2x,其中. |
若a的值使得x2+4x+a=(x+2)2﹣1成立,则a的值为 |
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A.5 B.4 C.3 D.2 |
已知2x﹣y=10,求代数式[(x2+y2)﹣(x﹣y)2+2y(x﹣y)]÷4y的值. |
化简求值:[(x+2y)2﹣(x+y)(3x﹣y)﹣5y2]÷2x,其中x=﹣2,y=. |
先化简,再求值:[(xy+2)(xy﹣2)﹣2(x2y2﹣2)]÷(xy),其中x=10,y=﹣. |
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