4x²+5x=81 x(x+5)=0 (2x-x)(x-1)=0 x(x+5)=5x-10 (3x-2)(x+1)=x(2x-1)

4x²+5x=81 x(x+5)=0 (2x-x)(x-1)=0 x(x+5)=5x-10 (3x-2)(x+1)=x(2x-1)
4x²+5x=81 x(x+5)=0 (2x-x)(x-1)=0 x(x+5)=5x-10 (3x-2)(x+1)=x(2x-1)

4x²+5x=81 x(x+5)=0 (2x-x)(x-1)=0 x(x+5)=5x-10 (3x-2)(x+1)=x(2x-1)
x1=(-5+根1321）/8或（-5-根1321）/8
x2=0或-5
x3=1或0
x4=无解
x5=-1+根3或-1-根3

x-2 x-1 x-2 x-3 2x-2 2x-1 2x-2 2x-3 3x-3 3x-2 4x-5 -1 x-2 x 1 0 0 -5x 5 -5x-3 r2

x1=(-5+根1321）/8或（-5-根1321）/8
x2=0或-5
x3=1或0或1/2
x4=无解
x5=-1+根3或-1-根3

x1=(-5+根1321）/8或（-5-根1321）/8
x2=0或-5
x3=1或0
x4=无解
x5=-1+根3或-1-根3