Question

Tìm x:

a).8x² - 5=67

b).(4x - 2)⁴=16

 

 

Answer 1

`#3107`

a)

`8x^2 - 5 = 67 `

`=> 8x^2 = 67 + 5`

`=> 8x^2 = 72`

`=> x^2 = 9`

`=> x^2 = (+-3)^2`

`=> x = +-3`

Vậy, `x \in {-3;3}`

b)

`(4x - 2)^4=16`

`=> (4x - 2) = (+-2)^4`

`=> ` TH1: `4x - 2 = 2`

`=> 4x = 4`

`=> x =1`

TH2: `4x - 2 = -2`

`=> 4x = 0`

`=> x=0`

Vậy, `x \in {0; 1}.`

Answer 2

a) \(8x^2-5=67\)

\(8x^2=72\)

\(x^2=9\)

\(x=3\)

Vậy x = 3

b) \(\left(4x-2\right)^4=16\)

\(\left(4x-2\right)^2=4\)

\(4x-2=2\)

\(4x=4\)

\(x=1\)

Vậy x = 1