Question

(x的二次方-mx+1)(x-2)的积中x的二次项系数为0,则m的值是多少

Answer 1

(x^2-mx+1)(x-2)

=x^3-mx^2+x-2x^2+2mx-2

=x^3-(m+2)x^2+(2m+1)x-2

x的二次项系数为-(m+2)=0

m=-2