已知x-2y=3,求1/2x²-2xy+2y²

来源：学生作业帮编辑：作业帮分类：数学作业时间：2024/11/07 23:42:46

已知x-2y=3,求1/2x²-2xy+2y²
还有一题、
已知 x²+y²=20，x²+xy-2y²=2（x+2y），求x+y的值

1/2x²-2xy+2y²
=1/2x²-xy-xy+2y²
=1/2x(x-2y)-y(x-2y)
=3/2x-3y
=3/2(x-2y)
=9/2

已知x/y=3,求x²+2xy-3y²/x²-2xy+y² 已知x/y=3,求x²+2xy-3y²/x²-xy+y²的值已知X²-5XY+6Y²=0,求(X²+3XY)\2Y²的值已知x/y=3,求x²+2xy-3y²/x²-xy+y³的值已知x-2y=3,求1/2x²-2xy+2y² 已知|x+2|+(y+1²=0,求x²+(2xy-3y²)-2(x²+xy-2y |x+2y+3|+(2x+y)²=0求x²-xy+y² 已知3x²+xy-2y²=0(x≠0,y≠0),求x/y-y/x-x²+y²/x 已知3x²+xy-2y²=0.求代数式y分之x-x分之y-xy分之x²+y²的值 x/y=2,求分式x²-xy+3y²/x²+xy+6y² 已知xy=-2,x-y=3,求(x+y)(x-y)-y²+(x-y)²-(6x²y-2xy 已知x-2y=3,x²-2xy+4y²=11,求①xy ②x²y-2xy²