题目

求3x方-2{x-5[x-3(x-2x方)-3(x方-2x)]-(x-1)}的值,其中x=2

提问时间：2021-03-26

答案

原式=3x²-2{x-5[x-3(x-2x²)-3(x²-2x)]-(x-1)}
=3x²-2[x-5(x-3x+6x²-3x²+6x)-x+1]
=3x²-2(x-5x+15x-30x²+15x²-30x-x+1)
=3x²-2x+10x-30x+60x²-30x²+60x+2x-2
=(3x²+60x²-30x²)+(-2x+10x-30x+60x+2x)-2
=33x²+40x-2
当x=2时
原式=33×2²+40×2-2
=33×4+80-2
=132+80-2
=210