x^2-4y^2+6x+9

81/8*(-x-y)^6*(x-y)^3*4/9(x+y)^4*(y-x)^2 (x+y)^2+6(x+y)+9 1.(x^3-x^2-4x+1)/(x^2-3x+2)-(x^3-2x^2-9x+21)/（x^2-5x+6）+（x^2-3x+8）/（x^2-4x+3）2.{(x^2)/（x-y)}*{y/(x+y)}-{(x^4y)/(x^4-y^4)}÷{（x^2/x^2+y^2）^2} 【2(x-y)(x-y)(x-y)-8(x-y)(x-y)(x+y)+6y(x-y)(x-y)]/2(x-y)(x-y) [(x+2y)(x-2y)+4(x-y)^2-6x]/(6x)计算 (66x^6y^3-24x^4y^2+9x^2y)÷(-3x^2y)化简 x^3y^2+6x^2y+9x (x-2y)^2-6(2y-x)(x+y)+9(x+y)^2因式分解 解二元一次方程 {3(x+y)-4(x-y)=-9 x+y/2+x-y/6=1 4x-y/2根号x+根号y 9x-6根号xy+y/3根号x-根号y 因式分解 （1）.(x+y)(x+y-6)+9 （2）.x²-16y²-x-4y 计算(x-y)^7÷(y-x)^6+9-x-y)^3÷(x+y)^2 9(x+y)-2(x+y)-6(x+y)+18(x+y)合并同类项 合并同类项：9(x+y)-2(x+y)-6(x+y)+18(x+y) 4x-3y/x-2y÷6y-8x/y-2x （x+y）/2- x-y/2=6 3(x+y)=4(x-y) x+y/3+x-y/2=6 4(x+y)-2(x-y)=40 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1