(y+3)(4y-1)

{3(x+y)+3(y+x)=1,3(x+y)+4(y-x)=-1 （x+2)(x+3) (x-4)(x+1) (y+4)(y-2) (y-5)(y-3) 解3y+5/3y-6=1/2+5y-4/2y-4 计算(2y+1)^2×(2y+1)^3+(2y+1)^4【-(2y+1)】 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 ｛4/(x+y)+6/(x-y)=3 ｛9/(x-y)-1/(x+y)=1 计算:1/(x-y)-1/(x+y)-2y/(x^2+y^2)-4y^3/(x^4+y^4)-8x^7/(x^8+y^8 [(2x+y)^2+(y+2x)(y-2x)-2y(4x-y)]/4y,其中x=1/2,y=1/3 微分方程(1)(y'')^2+5y'-y+x=0;(2)y''+5y'+4y^2-8x=0;(3)(3x+2y)dx+( 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 已知y²-3y+1=0,求下列分式的值 y²+（1/y²） y²/y的4次方+y 先化简,再求值：[(x+y)(x-y)-(x-y)^2+2y(x-3y)]/(-4y),其中x=1,y=-2