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1、9（2x-y）²-16（x+2y）²2、-14xy-x²-49y²3、（x²-2x）²-2x（2-x）+1
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1、9（2x-y）²-16（x+2y）² 2、-14xy-x²-49y² 3、（x²-2x）²-2x（2-x）+1
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答案和解析
解
9(2x-y)²-16(x+2y)²
=[3(2x-y)-4(x+2y)][3(2x-y)+4(x+2y)]
=(6x-3y-4x-8y)(6x-3y+4x+8y)
=(2x-11y)(10x+5y)
=5(2x-11y)(2x+y)
-14xy-x²-49y²
=-(x²+14xy+49y²)
=-(x+7y)²
(x²-2x)²-2x(2-x)+1
=(x²-2x²)²+2(x²-2x)+1
=[(x²-2x)+1]²
=(x²-2x+1)²
=[(x-1)²]²
=(x-1)^4
9(2x-y)²-16(x+2y)²
=[3(2x-y)-4(x+2y)][3(2x-y)+4(x+2y)]
=(6x-3y-4x-8y)(6x-3y+4x+8y)
=(2x-11y)(10x+5y)
=5(2x-11y)(2x+y)
-14xy-x²-49y²
=-(x²+14xy+49y²)
=-(x+7y)²
(x²-2x)²-2x(2-x)+1
=(x²-2x²)²+2(x²-2x)+1
=[(x²-2x)+1]²
=(x²-2x+1)²
=[(x-1)²]²
=(x-1)^4
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