问题
解答题
计算: (1)(2a-3b)(2a+3b)(-4a2-9b2) (2)(x-2y+3)(x+2y-3) (3)化简求值:
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答案
(1)原式=(4a2-9b2)(-4a2-9b2)
=81b4-16a4;
(2)原式=x2-4y2+12y-9;
(3)原式=
÷x(x-2) (x+1)(x-1) x2-1-2x+1 x+1
=
×x(x-2) (x+1)(x-1) x+1 x(x-2)
=
,1 x-1
当x=2时,原式=
=1.1 2-1