先化简,再求值 5(3a^2b-ab^2)-4(-ab^2+3a^2b) a=1/2 b= -1/3
问题描述：
先化简,再求值 5(3a^2b-ab^2)-4(-ab^2+3a^2b) a=1/2 b= -1/3
答
5(3a^2b-ab^2)-4(-ab^2+3a^2b)
=15a²b-5ab²+4ab²-12a²b
=3a²b-ab²
=ab(3a-b)
=-1/6*(3/2+1/3)
=-11/36
答
5(3a^2b-ab^2)-4(-ab^2+3a^2b)
=15a^2b-5ab^2+4ab^2-12a^2b
=3a²b-ab²
=3*(1/2)² *(-1/3)-1/2*(-1/3)²
=-1/4-1/18
=-11/36