Question

Tìm x

\(\left(x+2\right)^2=81\)

Answer 1

\(\left(x+2\right)^2=81\)

\(\Leftrightarrow\left(x+2\right)^2=9^2\)

\(\Leftrightarrow\left[\begin{matrix}x+2=9\\x+2=-9\end{matrix}\right.\Rightarrow\left[\begin{matrix}x=7\\x=-11\end{matrix}\right.\)

Answer 2

\(\left(x+2\right)^2=81\)

\(\left(x+2\right)^2=9^2\)

\(\rightarrow x+2=9\)

\(\rightarrow x=7\)

Vậy ............

Answer 3

\(\left(x+2\right)^2=81\)

\(\Rightarrow\left[\begin{matrix}x+2=9\\x+2=-9\end{matrix}\right.\)

\(\Rightarrow\left[\begin{matrix}x=7\\x=-11\end{matrix}\right.\)

Vậy x=7 hoặc x=-11

Answer 4

Mk lm lại nhs , mk thiếu trường hợp 2

\(\left(x+2\right)^2=81\)

\(\left(x+2\right)^2=9^2\) hoặc \(\left(x+2\right)^2=\left(-9\right)^2\)

=> x + 2 = 9 hoặc x + 2 = -9

Vậy \(x\in\left\{7;-11\right\}\)