Question

是一个多项式减去3x^2-5x+1.小赵同学由于粗心大意,将减号抄成加号得出结果是5x^2+3x-7.试求出这道题的正确

Answer 1

设被减数为x

x+3x^2-5x+1=5x^2+3x-7

x=5x^2+3x-7-(3x^2-5x+1)

x=5x^2+3x-7-3x^2+5x-1

x=2x^2+8x-8

2x^2+8x-8-(3x^2-5x+1)

原式=2x^2+8x-8-3x^2+5x-1

=-x^2+13x-9

答：这道题的正确答案是-x^2+13x-9