题目

(3a-4a^2+1+2a^3)-(-a+5a^2+3a^3),其中a=-1
先化简,在求值

提问时间：2020-06-15

答案

(3a-4a^2+1+2a^3)-(-a+5a^2+3a^3)
=3a-4a^2+1+2a^3+a-5a^2-3a^3
=3a+a-4a^2-5a^2+2a^3-3a^3+1
=4a-9a^2-a^3+1
=4*(-1)-9*(-1)^2-(-1)^3+1
=-4-9+1+1
=-11