计算.(1)(x-1)(x2+x+1);(2)-5x(-x2+2x+1)-(2x+3)(5-x2);(3)(3x-y)(y+3x)-(x-3y)(4x+3y).-数学

题目简介

计算.(1)(x-1)(x2+x+1);(2)-5x(-x2+2x+1)-(2x+3)(5-x2);(3)(3x-y)(y+3x)-(x-3y)(4x+3y).-数学

题目详情

计算.
(1)(x-1)(x2+x+1);
(2)-5x(-x2+2x+1)-(2x+3)(5-x2);
(3)(3x-y)(y+3x)-(x-3y)(4x+3y).
题型:解答题难度:中档来源:不详

答案

(1)原式=x3-1;
(2)原式=5x3-10x2-5x-(10x-2x3+15-3x2)
=5x3-10x2-5x-10x+2x3-15+3x 2
=7x3-7x2-12x-15;
(3)原式=9x2-y2-(4x2+3xy-12xy-9y2)
=9x2-y2-4x2-3xy+12xy+9y2
=5x2+8y2+9xy.

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