已知6x-1=2,y^2-y=2求(5x^2y+5xy-7x)-(4x^2+5xy-7x)的值

已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知:2x-y/x+y=1/5,求2x+5y/6x-2y的值 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 已知x+y=a,2x-y=-2a,求[（x/y-y/x)/(x+y)-x(1/x-1/y)]/[(x+1)/y]的值 已知x+y=-6,x-y=5,求x^2-y^2 已知2/y-5/x=16,5/y+6/x=13,求x、y. 已知x>0,y>0,2/x+5/y=1,求x+y最小值 已知X*X+Y*Y+6X-8Y+25=0 求（Y/X)+(X/Y)-2=? 1、(-y^3)^5/y^3/ y^2+2(-y)^102、(x-y)^7/(y-x)^6+(x+y)^3/(x+y)^23、已知X^a=5,x^b=3,求X^(3a-2b)的值 已知x+y=-1,xy=-2,求代数式-5（x+y)+(x-y)+x(xy+y)的值 已知y = |2x-6| + |x-1| - 4|x+1| ,求y已知y = |2x-6| + |x-1| - 4|x+1| ,求y的最大值 1.y=x^5+5^x+x^x+lgx 2.y=xe^x^2求y'' 3.已知y=e^f(x),则y''= 4.已知y=(1+x)^x,求导数y' 已知x-y=1,求[(x+2y)^2+(2x+y)(x-4y)-3(x+y)(x-y)]除以y的值大神们帮帮忙 已知:【(x²+y²)-(x-y)²+2y(x-y)】/4y=1,求4x/4x²-y²-1/2x+y 已知x-y=1,求[(x+2y)²+(2x+y)(x-4y)-3(x+y)(x-y)]÷y的值 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² 已知|x|=2,|y|=3,|x+y|=-(x+y)求x-y