Question

\(\sqrt{4x^2}=\sqrt{x+5}\)

Answer 1

\(\sqrt{4x^2}=\sqrt{x+5}\left(đk:x\ge-5\right)\)

\(\Leftrightarrow4x^2=x+5\)

\(\Leftrightarrow4x^2-x-5=0\)

\(\Leftrightarrow\left(4x-5\right)\left(x+1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{4}\\x=-1\end{matrix}\right.\)

Answer 2

ĐKXĐ: x >= -5

Pt <=> 4x^2 = x + 5

<=> 4x^2 - x - 5 = 0

<=> (x + 1)(4x - 5) = 0

<=> x + 1 = 0 hoặc 4x - 5 = 0

<=> x = -1 hoặc x = 5/4 (thỏa ĐKXĐ)

 

Answer 3

2x=x+5

2x-x=5

x=5