Question

Bài 1:Tìm x ∈ Z,biết:

a)(x+5)²=100

b)(2x -4)²=0

c)(x-1)³=27

Mn ơi gp mk vs

Answer 1

Bài 1:

a) Ta có: \(\left(x+5\right)^2=100\)

\(\Leftrightarrow\left[{}\begin{matrix}x+5=10\\x+5=-10\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=5\\x=-15\end{matrix}\right.\)

Vậy: \(x\in\left\{5;-15\right\}\)

b) Ta có: \(\left(2x-4\right)^2=0\)

\(\Leftrightarrow2x-4=0\)

\(\Leftrightarrow2x=4\)

hay x=2

Vậy: x=2

c) Ta có: \(\left(x-1\right)^3=27\)

\(\Leftrightarrow x-1=3\)

hay x=4

Vậy: x=4

Answer 2

=))

Answer 3

a) (x+5)²=100

=> \(\left\{{}\begin{matrix}x+5=10\\x+5=-10\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=5\\x=-15\end{matrix}\right.\)

b) (2x-4)²=0

=> 2x-4=0

=> 2x=4 => x=2

c) (x-1)³=27

=>x-1=3 =>x=4