3(y-3)-5(1+y)=7(y-1)

解方程：3y^2-(2y+1)(y-1)=(y-5)(y+1) 解方程3y^2-(2y+1)(y-2)=(y-5)(y-1) (5y+1)+ (1-y)= (9y+1)+ (1-3y); 解3y+5/3y-6=1/2+5y-4/2y-4 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 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 (y/3)-1=(-5+7y)/3 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 (3y-1)/4-1=(5y-7)/6 9y-3-3=10y-14 9y-10y=-14+3+3 -y=-8 y=8 解方程:4(2y+3)=8(1-y)-5(y-2) 解8y+3=8-y-5y+2 14y=7 所以y=1/2 错在：原因 7x-3y/5=5x-y/3-x+y/2 x-1/5=y+1/3