几道数学题，在线等待

1.6x4+5x3-38x2+5x+6=0,则6x4+5x3-（39-1）x2+5x+6=0，
得（x+3）(6x3-13x2+x+2)=（x+3）(6x3-13x2+(2-1)x+2)=
（x+3）(x-2)(6x2-x-1)=（x+3）(x-2)（2x-1)(3x+1)=0
x=-3,2,1/2,-1/3
2.(x2+2x-3)(x2+2x-8)=84,(x2+2x)^2-11x-60=0,(x2+2x-15)*(x2+2x+4)=0,
x=-5,3
3.x4+x4-16x3+96x2-256x3+256=626,x4-8x3+48x2-128x-185=x4-8x3+(57-9)x2-128x-185=(x+1)(x-9)x2+(x+1)(57x-185)=0
(x+1)(x3-9x2+57x-185)=(x+1)[x3-9x2+(20+37)x-185]=(x+1)(x-5)(x2-4x+37)=0
解得：x=5，-1

可算算出来了！！

2.x=3或x=-5

1.x=6.2
2.x=3
3.x=5

2. (x-1)(x+3)(x-2)(x+4)=84
（x^2+2x-3)(x^2+2x-8)=84
换元设x^2+2x=t
即(t-3)(t-8)=84
t^2-11t-60=0
t=15 t=-4
x^2+2x-15=0 x=-5 x=3
x^2+2x+4=0 x无解
综上 -5或3