计算:[(x+y)(x-y)-(x+y)2-2y(x-2y)]÷(-2y)
题型:解答题难度:一般来源:不详
计算:[(x+y)(x-y)-(x+y)2-2y(x-2y)]÷(-2y) |
答案
[(x+y)(x-y)-(x+y)2-2y(x-2y)]÷(-2y), =(x2-y2-x2-2xy-y2-2xy+4y2)÷(-2y), =(2y2-4xy)÷(-2y), =-y+2x. |
举一反三
先化简,再求值: (1)3(a+1)2-(a+1)(2a-1),其中a=1. (2)(a+1)2-a(a+3),其中a=2. |
先化简:(2x-1)2+(x+2)(x-2)-4x(x-1),再求值,其中x=. |
先化简,再求值:(a2b-2ab2-b3)÷b-(a-b)(a+b),其中a=-2,b=. |
下列计算正确的是( )A.2a2+a3=3a5 | B.2x•3x5=6x6 | C.(2b2)3=8b5 | D.(3xy)2÷(xy)=3xy |
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