(8a^3b-5a^2b^2)/4ab怎么做?
问题描述：
(8a^3b-5a^2b^2)/4ab怎么做?
还有(x+2y-3)(x-2y+3)
[(x-2y)^2+(x-2y)(2y+x)-2x(2x-y)]/2x共三道题,
答
(8a^3b-5a^2b^2)/4ab
=8a^3b/4ab-5a^2b^2/4ab
=2a^2-5ab/4
(x+2y-3)(x-2y+3)
=[x+(2y-3)]*[x-(2y-3)]
=x^2-(2y-3)^2
=x^2-4y^2+12y-9
[(x-2y)^2+(x-2y)(2y+x)-2x(2x-y)]/2x
=[x^2-4xy+4y^2+x^2-4y^2-4x^2+2xy]/2x
=[-2x^2-2xy]/2x
=-x-y