Question

Tìm x

(2-x)²-(x+5)²=0

4x²-1-x(2x+1)=0

Answer 1

Tìm x

(2 - x)² - (x + 5)² = 0

<=> (4 - 4x + x²) - (x² + 10x + 25) = 0

<=> 4 - 4x + x² - x² - 10x - 25 = 0

<=> -14x - 21 = 0

<=> -14x = 21

<=> x = -1,5

Vậy ....................

4x² - 1 - x(2x + 1) = 0

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

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

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

\(\Leftrightarrow\left[{}\begin{matrix}2x+1=0\\x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x=1\end{matrix}\right.\)

Vậy ...................