(1).(1/2x-1/3y^2)(-1/2x-1/3y^2)

题目

(1).(1/2x-1/3y^2)(-1/2x-1/3y^2)
(2).(2a+b)(2a-b)
(3).先化简,再求值:y(x+y)+(x+y)(x-y)-x^2,其中x=-2,y=1/2

答案

(1).(1/2x-1/3y^2)(-1/2x-1/3y^2)
=-1/4x^2+1/9y^4
(2).(2a+b)(2a-b)
=4a^2-b^2
(3).y(x+y)+(x+y)(x-y)-x^2 其中x=-2,y=1/2
=(x+y)x-x^2
=x(x+y-x)
=xy
=-1,