x+y=20,为什么x² - y² =20(x-y)
x(x-y)-y(y-x)+(x-y)²因式分解
因式分解 -5x³y(x-y)³+20y【x²(y-x)】²
已知x²-y²=20,且x+y=5,则x-y的值
已知x+y=4,x²-y²=20,则x-y=?
解方程组x+y+√(x+y)=20;x²+y²=136
已知x-y=4,x²-y²=20,求x-y的值
[(2x+y)²-y(y+4x)-8x] ÷2x 其中x=2,y=-1
若|x+2y-1|+y²+4y+4=0,求(2x-y)²-2(2x-y)(x+2y)+(x+2y)&
已知x²+y²-8x+6y+25=0,求(x-y+4xy/x-y)(x+y-4xy/x+y)
若|x+y-1|+(x-y-2)²=0,求代数式(x+2y)(x-2y)-(2x-y)(-y-2x)的值.
2.(x+y)²(x-y)²-(x-y)(x+y)(x²+y²)
[(2x+3y)²-(y+2x)(2x-y)-10y(x+y+1)÷2y其中x=2019,y=20