如何计算3(2x²-y²-1)-2(3y²-2x²+2)
计算:(1)2/(x+y)+4y/x²-y²(2)x²/x+y-x+y
已知x-y=1,y≠0,求{(x+2y)²+(2x+y)(x+4y)-3(x+y)(x-y)}÷y的值.
计算:【[2/(3x)-2/(x+y)×[(x+y/(3x)-x²-xy)]】÷(x-y)/x
计算3x[xy-2x(1/y-x/3]+3y(x²-y²)
数学用乘法公式计算(x+y+1)(x+y-1)(2x-y-3)²
计算:(2x+y)²-(x+2y)²(要过程)
因式分解x²(x-2y)+y²(2y-x)
简便计算:(1)(x-2y)(-x+2y) (2)(x+y-2)²
12x²-3y² (2x+y)²-(x+2y)²
计算:[(x+¼y)+(x-¼y)](2x²-1/8y²)
先化简,再求值:x²/x-y-y²/x-y,其中x=1+2又根号3
[(3x+y)²-(3x-y)²]÷(4x-2y)计算 怎么做?