Question

要是多项式mx*x*x+3nxy²+2x*x*x-xy²+y不含三次式,则2m+3n的值为多少.

Answer 1

多项式mx*x*x+3nxy²+2x*x*x-xy²+y不含三次式

mx*x*x+3nxy²+2x*x*x-xy²+y

=(m+2)x^3+(3n-1)xy²+y

m+2=0 3n-1=0

m=-2 n=1/3

2m+3n

=2*(-2)+3*1/3

=-3