11/9y+2/7=2/9y-5/7 1/2{x-1/2(x-1)}=2/3(x-1) 2x-1/3=1+4x/5-1

y=(x-1)(x-2)(x-3)(x-4)(x-5)(x-6)(x-7)(x-8)(x-9)(x-10)的导数在x=1 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y x+y=3 x+2y=9 3/x+1=y y-x=3 y=2x-3 y-3x=1 2(x+1)-y=6 7x-5y=-9 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( 9y=3x-(x-1),4(x+y)-(2x+4)=8y 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 已知4x=9y求(1)x+y/y (2)y-x/2x {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 函数,y=3x/(x^2+x+1) ,x 函数y=3x/(x^2+x+1) （x 有几道题想请教一下7x=6x-4 x-15=74 3x=2x+5 -5x=8-4x 9y=6y-6 8x=4x+1 7x