Question

[kudo]

tìm x : giúp

\(\left(2x+5\right)^2=\frac{9}{25}\)

Answer 1

[Trịnh Thuý Hiền]

\(\left(2x+5\right)^2=\left(\frac{3}{5}\right)^2\)

\(\Rightarrow\orbr{\begin{cases}2x+5=\frac{3}{5}\\2x+5=\frac{-3}{5}\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}2x=\frac{-22}{5}\\2x=\frac{-28}{5}\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=\frac{-11}{5}\\x=\frac{-14}{5}\end{cases}}\)

Answer 2

[Nguyễn Phương Thảo]

(2x+5)² = \(\frac{9}{25}\)= (3/5)²

\(\Rightarrow\)2x+5=3/5 hoặc 2x+5=-3/5
\(\Rightarrow\)x=-11/5 hoặc x=-14/5
Vậy x\(\in\){-11/5 ; -14/5}