`3x^2 = 108` Solve the equation.

2 Answers | Add Yours

violy's profile pic

violy | High School Teacher | (Level 1) Associate Educator

Posted on

There are two ways to solve this.
1. Since we are solving for `x` , we need to isolate the term with x.
The `3` is being multiplied on left side, we will apply the opposite operation of multiplication, which is division.
Divide both sides by `3` .
`(3x^2)/3 = 108/3`

`x^2 = 36`

Taking the square root of both sides.
`sqrt(x^2) = +- sqrt(36)`

`x = +- 6`

2. Making the right side equal to `0 ` by subtracting `108` on both sides.
`3x^2 - 108 = 108 - 108`

`3x^2 - 108 = 0`

Factor out the `3` on left side.
`3(x^2 - 36) = 0`

Divide both sides by `3` .
`x^2 - 36 = 0`

Factor the left side.
`(x - 6)(x + 6) = 0`

Equate each factor to `0` .
`x - 6 = 0`
`x = 6`

or

`x + 6 = 0`
`x = -6`

Therefore `x = {6, - 6}` .
That is it!

Educator Approved

Educator Approved
iamkaori's profile picture

iamkaori | Student, Grade 9 | (Level 2) Salutatorian

Posted on

divide both sides by 3:

x^2 = 36

square root both sides:

x = +-6

We’ve answered 318,912 questions. We can answer yours, too.

Ask a question