数学二次函数的画图{y=3x^2,y=3x^2-1,y=3x^2+1{y=-1/3x^2,y=-1/3x^2+2,y=-

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 (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 2(x+y) 3x+3y=24 x+y/2x x y/2y= 1 函数,y=3x/(x^2+x+1) ,x 函数y=3x/(x^2+x+1) （x 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 画图：1:y=｜x^2-2x-3 ｜ 2:y=2^｜x ｜-1 数学书解方程组{2(x+y)-(x-y)=3,（x+y)-2(x-y)=1 1奥数题x-2y/x+2y=3,求x-2y/3(x+2y)-3(x-2y)/x-2y的差 若x=-1/4,能否确定代数式(2x-y)(2x+y)+(2x-y)(y-4x)+2y(y-3x)的值? 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-(