Question

giải pt:

a.

\(3\left(x^2+x^2\right)-2\left(x^2+x\right)-1=0\)

b.

\(\left(x^2-4x+2\right)^2+x^2-4x-4\)

Answer 1

6x2-4x2-1=0

2x2-1=0

2x2=1

X=1/4

Answer 2

\(a,3\left(x^2+x^2\right)-2\left(x^2+x\right)-1=0\)

\(\Leftrightarrow4x^2-2x-1=0\)

\(\Delta^'=1+4=5\)

vì \(\Delta^'>0=>\)phường trình có 2 nghiệm phân biệt

\(\left\{{}\begin{matrix}x_1=\dfrac{1+\sqrt{5}}{4}\\x_2=\dfrac{1-\sqrt{5}}{4}\end{matrix}\right.\)

b, \(\left(x^2-4x+2\right)^2+x^2-4x-4=0\)

\(\Leftrightarrow x^4-8x^3+20x^2-16x+4+x^2-4x-4=0\)

\(\Leftrightarrow x^4-8x^3+21x^2-20x=0\)