计算(1)、x²y-3x²y (2)、10y²+0.5y² (3)、-1/2a&
运用乘法公式计算:(1)(x-y)(x+y)-(2x-y)²
先化简再求值:(x-2y)²-(x+2y)(x-2y)-(x-3y)(x-y).其中x²+9y
计算3x[xy-2x(1/y-x/3]+3y(x²-y²)
计算:(x+2y)(3x-5y)-(6x的四次方y²-2x²y²)÷(2x²y&
计算:(1)2/(x+y)+4y/x²-y²(2)x²/x+y-x+y
数学用乘法公式计算(x+y+1)(x+y-1)(2x-y-3)²
若|x+2y-1|+y²+4y+4=0,求(2x-y)²-2(2x-y)(x+2y)+(x+2y)&
已知x-y=1,y≠0,求{(x+2y)²+(2x+y)(x+4y)-3(x+y)(x-y)}÷y的值.
(1):(x+2y)²-(x+y)(3x-y) (2):(2x+3y)²-(2x-3y)²
初一几道计算忘了.x²-5x=2a(x-2y)-3b(2y-x)-4c(x-2y)=-5x²y
(1)已知x+y=6,x²-y²=5,求x-y的值(2)若x+y=3,x²+y²
[(2x+3y)²-(y+2x)(2x-y)-10y(x+y+1)÷2y其中x=2019,y=20