Question

How do you solve `16- 4x ^ { 2} = - 20`?

Answer 1

`x=+-3`

Explanation:

`"subtract 16 from both sides"`

`cancel(16)cancel(-16)-4x^2=-20-16`

`rArr-4x^2=-36larr" multiply through by - 1"`

`rArr4x^2=36`

`"divide both sides by 4"`

`(cancel(4)color(white)(x)x^2)/cancel(4)=36/4`

`rArrx^2=9`

`color(blue)"take the square root of both sides"`

`sqrt(x^2)=+-sqrt9larrcolor(red)" note plus or minus"`

`rArrx=+-3`