Question

若多项式2mx^3+3nxy^2-2x^3-xy^2+y中不含三次项,则2m+3n=?

Answer 1

2mx^3+3nxy^2-2x^3-xy^2+y中不含三次项

所以 不包含 2mx^3+3nxy^2-2x^3-xy^2 这四项

2mx^3+3nxy^2-2x^3-xy^2

=（2m-2）x^3+(3n-1)xy^2

=0

所以2m-2=0 3n-1=0

所以m=1 n=3分之1

2m+3n=2+1=3