Question

[4a^2b^2(3b^2-5ab)-a^2(-2b)^3]/8a^2b^3

（5*10^5）*(-6*10^-2)/(-1/2*10^-2)=？

[(1/2x+y)^2-(1/2x-y)^2]/(-4xy)=?

已知a+b=2/3 ，ab=2求代数式a^2b+2a^b^2+ab^3的值

已知A=3x^2-2y+1 B=x^2-y 求（1）A-2B （2）A*B
求速度 快的加分！

Answer 1

解 原式=4a^2b^3(3b^2-5a+2)/(8a^2b^3).
=(1/2)(3b^2-5a+2).

原式=5*(-6)*(-2)(10^(5-2+2).
=60*10^5.
=6*10^6.
原式=[(1/2x+y+1/2x-y)(1/2x+y-(1/2x-y)]/(-4xy.
=2xy/(-4xy).
=-1/2.
原式=a^3b+2a^2b^2+ab^3 . [原题求: a^2b+2a^b^2+ab^3,可能有误]
=ab(a^2+2ab+b^2)
=ab(a+b)^2.
=2*(2/3)^2.
=8/9.
已知: A=3x^2-2y+1. B=x^2-y,
求(1) A-2B.
A-2B=3x^2-2y+1-2*(x^2-y).
=3x^2-2y+1-2x^2+2y.
=x^2+1.
(2) A*B=(3x^2-2y+1)*(x^2-y)
=3x^4-3x^2y-2x^2y+2y^2+x^2-y.
=3x^4-5x^2y+x^2-y+2y^2.
=3x^4-(5y-1)x^2+2y^2-y.