当X=4,(x-2)(x-3)+(x-4)(x-5 - 知识问答

当X=4,(x-2)(x-3)+(x-4)(x-5)-2(x+5)(x-6)求它的值.解答及过程

2个回答

(x-2)(x-3)+(x-4)(x-5)-2(x+5)(x-6)
=(x²-5x+6)+(x²-9x+20)-2(x²-x-30)
=x²-5x+6+x²-9x+20-2x²+2x+60
=-12x+86
=-12×4+86
=-48+86
=38

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