Question

[mit béo]

Tìm x; biết:

f.x³ – 7x² = – 6x                                           g.(x + 1)(x + 2)(x + 4)(x + 5) = 4              

     h.(x² – 0,5) : 2x – (3x – 1)² : (3x – 1) = 0

     i. (x + 3)(x² – 3x + 9) – x(x – 2)(x + 2) = 15

Answer 1

[Nguyễn Lê Phước Thịnh]

g: \(\Leftrightarrow\left(x^2+6x+5\right)\left(x^2+6x+8\right)-4=0\)

\(\Leftrightarrow\left(x^2+6x\right)^2+13\left(x^2+6x\right)+36=0\)

\(\Leftrightarrow\left(x+3\right)^2\left(x^2+6x+4\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=\sqrt{5}-3\\x=-\sqrt{5}-3\end{matrix}\right.\)