Question

Answer 1

`@` `\text {Ans}`

`\downarrow`

`a)`

\((x-1)^3=27\)

`=> (x-1)^3=3^3`

`=> x-1=3`

`=> x=3+1`

`=> x=4`

Vậy, `x=4`

`b)`

\((2x+1)^2=25\)

`=> (2x+1)^2=(+-5)^2`

`=>`\(\left[{}\begin{matrix}2x+1=5\\2x+1=-5\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}2x=4\\2x=-6\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x=2\\x=-3\end{matrix}\right.\)

Vậy, `x \in {2; -3}`

`c)`

\(5^{x+2}=625\)

`=>`\(5^{x+2}=5^4\)

`=> x+2=4`

`=> x=4-2`

`=> x=2`

Vậy, `x=2.`

Answer 2

8:

a: =>x-1=3

=>x=4

b: =>2x+1=5 hoặc 2x+1=-5

=>x=2 hoặc x=-3

c: =>x+2=4

=>x=2