1.已知x=-2,y=1求代数式2(x-3y)^2-(x-3y)(x+3y)的值
问题描述：
1.已知x=-2,y=1求代数式2(x-3y)^2-(x-3y)(x+3y)的值
2.已知一个三角形的面积是(4a^3b-6a^2b^2+12ab^3),一边长为2ab,求该边上的高
3.已知2x-y=10,求[X^2+y^2-(x-y)^2+2y(x-y)]÷4y的值.【求完整解题过程,急用,】
答
2(x-3y)^2-(x-3y)(x+3y)
=(x-3y)(2x-6y-x-3y)
=(x-3y)(x-9y)
当x=-2,y=1时
原式=（-2-3)(-2-9)=-5×(-11)=55
(4a^3b-6a^2b^2+12ab^3)÷2ab×2
=(2a²-3ab+6b²)×2
=4a²-6ab+12b²
[X^2+y^2-(x-y)^2+2y(x-y)]÷4y
=(x²+y²-x²+2xy-y²+2xy-2y²)÷4y
=(4xy-2y²)÷4y
=(2x-y)/2
=10/2
=5