Question

Giải giúp em câu 12,13,14 với ạ

Answer 1

Answer 2

12: Ta có: \(\sqrt{3x+5^2}=7\)

\(\Leftrightarrow3x+25=49\)

hay x=8

13: Ta có: \(\sqrt{x^2-10x+25}=4\)

\(\Leftrightarrow\left|x-5\right|=4\)

\(\Leftrightarrow\left[{}\begin{matrix}x-5=4\\x-5=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=9\\x=1\end{matrix}\right.\)

Answer 3

11: Ta có: \(\sqrt{2x-3}=7\)

\(\Leftrightarrow2x-3=49\)

\(\Leftrightarrow2x=52\)

hay x=26

14: Ta có: \(\sqrt{x^2-x+11}=x+2\)

\(\Leftrightarrow x^2+4x+4-x^2+x-11=0\)

\(\Leftrightarrow5x=7\)

hay \(x=\dfrac{7}{5}\)