Question

[Cầm Dương]

Giải phương trình 

\(6x^4+7x^3-36x^2-7x+6=0\)

Answer 1

[Nguyễn Hương Giang]

6x⁴+7x³-36x²-7x+6=0

<=> 6x⁴-2x³+9x³-3x²-33x²+11x-18x+6=0

<=> 2x³(3x-1)+3x²(3x-1)-11x(3x-1)-6(3x-1)=0

<=> (3x-1)(2x³+3x²-11x-6)=0

<=>(3x-1)(2x³-4x²+7x²-14x+3x-6)=0

<=>(3x-1)[2x²(x-2)+7x(x-2)+3(x-2)]=0

<=>(3x-1)(x-2)(2x²+7x+3)=0

<=>(3x-1)(x-2)(2x²+6x+x+3)=0

<=>(3x-1)(x-2)[2x(x+3)+(x+3)]=0

<=>(3x-1)(x-2)(x+3)(2x+1)=0

th1: 3x+1=0 <=> x=\(-\frac{1}{3}\)

th2: x-2=0 <=> x=2

th3: x+3=0 <=> x=-3

th4: 2x+1=0 <=> x=-\(\frac{1}{2}\)