Question

[LUFFY WANO]

giúp em vơi em caần ngâấp ạp

Answer 1

[HT.Phong (9A5)]

a) \(\left(x+5\right)^2=36\)

\(\Rightarrow\left(x+5\right)^2=6^2\)

\(\Rightarrow\left[{}\begin{matrix}x+5=6\\x+5=-6\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=6-5\\x=-6-5\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=1\\x=-11\end{matrix}\right.\)

b) \(\left(2x-5\right)^3=64\)

\(\Rightarrow\left(2x-5\right)^3=4^3\)

\(\Rightarrow2x-5=4\)

\(\Rightarrow2x=4+5\)

\(\Rightarrow2x=9\)

\(\Rightarrow x=\dfrac{9}{2}\)

c) \(x^2=2\)

\(\Rightarrow x^2=\left(\sqrt{2}\right)^2\)

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

d) \(\left(3x-1\right)^2=5\)

\(\Rightarrow\left(3x-1\right)^2=\left(\sqrt{5}\right)^2\)

\(\Rightarrow\left[{}\begin{matrix}3x-1=\sqrt{5}\\3x-1=-\sqrt{5}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}3x=1+\sqrt{5}\\3x=1-\sqrt{5}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{1+\sqrt{5}}{3}\\x=\dfrac{1-\sqrt{5}}{3}\end{matrix}\right.\)

Answer 2

[Nguyễn Lê Phước Thịnh]

a: =>x+5=6 hoặc x+5=-6

=>x=-11 hoặc x=1

b: (2x-5)^3=64

=>(2x-5)^3=4^3

=>2x-5=4

=>2x=9

=>x=9/2

c: x^2=2

=>\(x^2=\left(\sqrt{2}\right)^2\)

=>\(x=\pm\sqrt{2}\)

d: (3x-1)^2=5

=>\(\left[{}\begin{matrix}3x-1=\sqrt{5}\\3x-1=-\sqrt{5}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}3x=\sqrt{5}+1\\3x=-\sqrt{5}+1\end{matrix}\right.\)

=>\(x=\dfrac{\pm\sqrt{5}+1}{3}\)