Question

这个方程怎么解？高中数学

求数列的~希望详细一点

Answer 1

f(x)=3x^4-2x^3-9x^2+12x-4
f(1)=0
3x^4-2x^3-9x^2+12x-4 =(x-1)(3x^3+ax^2+bx+4)
coef. of x:
4-b=12
b=-8
coef. of x^2
b-a=-9
-8-a=-9
a=1
3x^4-2x^3-9x^2+12x-4
=(x-1)(3x^3+x^2-8x+4)
g(x)= 3x^3+x^2-8x+4
g(1)= 0
3x^3+x^2-8x+4 = (x-1)(3x^2+cx-4)
coef. of x
-4-c=-8
c=4
3x^3+x^2-8x+4 = (x-1)(3x^2+4x-4)
3x^4-2x^3-9x^2+12x-4=0
(x-1)^2. (3x^2+4x-4) =0
(x-1)^2.(x-2)(3x+2)=0
x=1 or 2 or -2/3