(3a-4a^2+1+2a^3)-(-a+5a^2+3a^3),其中a=-1先化简,在求值
问题描述：
(3a-4a^2+1+2a^3)-(-a+5a^2+3a^3),其中a=-1
先化简,在求值
答
(3a-4a^2+1+2a^3)-(-a+5a^2+3a^3)
=-a^3-9a^2+4a+1
=1-9-4+1
=-11
答
(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