题目内容
化简和计算
(1)x(x+2y)-2(x2-xy+2)
(2)(2x-1)(x+2)-(x-2)2-(x+2)2,其中x=-1
.
(1)x(x+2y)-2(x2-xy+2)
(2)(2x-1)(x+2)-(x-2)2-(x+2)2,其中x=-1
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(1)原式=x2+2xy-2x2+2xy-4=-x2+4xy-4;
(2)原式=2x2+4x-x-2-x2+4x-4-x2-4x-4=4x-10,
当x=-1
时,原式=-6-10=-16.
(2)原式=2x2+4x-x-2-x2+4x-4-x2-4x-4=4x-10,
当x=-1
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