Question

How do you solve `3x² = 21`?

Answer 1

`color(green)( x = +sqrt7`
`color(green)( x = -sqrt7`

Explanation:

`3x² = 21`

`3x² - 21=0`
Here `3` is common to both terms:

`3(x² - 7)=0`

`x² - 7=0`

`x² = 7`
`x = +-sqrt7`

The solutions are:
`color(green)( x = +sqrt7 , x = -sqrt7`