(1/2x+1/3y)(1/3y-1/2x)+1/2x*(1/2x-1/3y),其中x=4,y=6先化简,再求值
问题描述：
(1/2x+1/3y)(1/3y-1/2x)+1/2x*(1/2x-1/3y),其中x=4,y=6先化简,再求值
答
(1/2x+1/3y)(1/3y-1/2x)+1/2x*(1/2x-1/3y),
=-（（1/2x）^2-(1/3y)^2）+（1/2x）^2-1/6XY
=-1/4x^2+1/9y^2+1/4X^2-1/6Xy
=1/9y^2-1/6Xy
所以x=4,y=6
1/9y^2-1/6Xy
=1/9*36-1/6*4*6
=4-4
=0
希望对你有帮助
答
(1/2x+1/3y)(1/3y-1/2x)+1/2x*(1/2x-1/3y)
=(1/3y+1/2x)(1/3y-1/2x)+1/2x(1/2x-1/3y)
=(1/3y+1/2x)(1/3y-1/2x)-1/2x(1/3y-1/2x)
=(1/3y-1/2x)(1/3y+1/2x-1/2x)
=1/3y(1/3y-1/2x)
=1/9y^2-1/6xy
=1/9×36-1/6×4×6
=4-4
=0