问题
解答题
已知-5x2m-1yn与11xn+2y-4-3m的积与x7y是同类项,试求出2n-m-9的值.
答案
-5x2m-1yn•11xn+2y-4-3m
=-55x2m-1+n+2yn-4-3m
∵与x7y是同类项,
∴由同类项的定义,得2m-1+n+2=7 n-4-3m=1
解得:
.m= 1 5 n= 28 5
∴2n-m-9
=2×
-28 5
-91 5
=2.
已知-5x2m-1yn与11xn+2y-4-3m的积与x7y是同类项,试求出2n-m-9的值.
-5x2m-1yn•11xn+2y-4-3m
=-55x2m-1+n+2yn-4-3m
∵与x7y是同类项,
∴由同类项的定义,得2m-1+n+2=7 n-4-3m=1
解得:
.m= 1 5 n= 28 5
∴2n-m-9
=2×
-28 5
-91 5
=2.