计算:(1)(x+3)(x+4)+(x-5)(x+5)-2(x-3)2;(2)9992+1998.-数学

题目简介

计算:(1)(x+3)(x+4)+(x-5)(x+5)-2(x-3)2;(2)9992+1998.-数学

题目详情

计算:(1)(x+3)(x+4)+(x-5)(x+5)-2(x-3)2
(2)9992+1998.
题型:解答题难度:中档来源:不详

答案

(1)原式=x2+7x+12+x2-25-2x2+12x-18,
=(1+1-2)x2+(7+12)x+(12-25-18),
=19x-31;

(2)原式=2+1998,
=10002-2×1000+1+1998,
=1000000-2000+1999,
=1000000-1,
=199999.

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