y=-x^2+2x+3=-(x^2-2x+1)+4=-(x-1)^2+4交点式化成顶点式谁给我说说这怎么化的

3^x+2x=y,x x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 函数,y=3x/(x^2+x+1) ,x 函数y=3x/(x^2+x+1) （x (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= (x+y)(x-y)+(x-y)平方-(x-y)(3x-y) 其中x=-2 y=3分之一 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) (x+y)(2x-3y)=? y=x^2-2x（x y=x^2+2x(x (x^3-2x^2+xy^2)/(x-y)+(x+y)(y-x)=? 若2x=3y,则(x*x+y*y)/x*x=? 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 y=(2x*x-2x+3)/(x*x-x+1),求值域? [2/3x-2/x+y(x+y/3x-x-y)]/x-y/x 化简：{2/3x-2/(x+y)[(x+y)/3x-x-y]}/(x+y)/x 计算2/3x-2/x+y(x+y/3x-x-y)/x-y/x 化简3x-2/(x+y)[(x+y)/3x-x-y]÷(x-y)/x