若(-7x的m+2次方)y²与-3x³(y的n次方)是同类项,则m-n=______.
问题描述:
若(-7x的m+2次方)y²与-3x³(y的n次方)是同类项,则m-n=______.
答
若(-7x的m+2次方)y²与-3x³(y的n次方)是同类项,
则m+2=3 m=1
n=2
所以m-n=1-2=-1