当a=-1时,式子-5a^n-a^n+8a^n-3a^n-a^(n+1)(n是正整数）等于多少
问题描述：
当a=-1时,式子-5a^n-a^n+8a^n-3a^n-a^(n+1)(n是正整数）等于多少
答
-5a^n-a^n+8a^n-3a^n-a^(n+1)
=-a^n-a^(n+1)
=-a^n*(a+1)
当a=-1时,a+1=0.所以
-5a^n-a^n+8a^n-3a^n-a^(n+1)=0