Question

How do you solve `7x^2-6=57`?

Answer 1

`x=+3 orx =-3`

Explanation:

There is no term in `x`, so you can solve for `x^2`

`7x^2 = 57+6" "larr` add 6 to both sides.

`7x^2 = 63" "larr div 7`

`x^2 =9`

`x= +-sqrt9`

`x =+-3`

Answer 2

Solution: `x=3 , x = -3`

Explanation:

`7x^2 -6 = 57 or 7x^2 =57+6 or 7x^2 =63` or

`x^2 =63/7 or x^2 =9 or x = +- sqrt 9 or x = +-3`

Solution: `x=3 , x = -3` [Ans]

Answer 3

`x=3` or `x=-3`

Explanation:

First, we add `6` to both sides.
`7x^2-6=57`
`7x^2-6color(blue)+color(blue)6=57color(blue)+color(blue)6`
Simplify:
`7x^2=63`

Divide both sides by `7`

`(7x^2)/7=63/7`

Therefore, `x^2=9`

If `x^2=a`, then `x=sqrta` or `-sqrta`.

`9=3^2`
`x=sqrt(3^2)`
`x=3`

or

`x=-sqrt9`
`x=-sqrt(3^2)`
`x=-3`

Both ways work.

Answer 4

`x=+-3`

Explanation:

If
`color(white)("XXX")7x^2-6=57`
then
`color(white)("XXX")7x^2=63` ...after adding `6` to both sides
and
`color(white)("XXX")x^2=9` ...after dividing both sides by `7`

Therefore
`color(white)("XXX")x=+3" or " x=-3` ...after taking the square root of both sides (since `(+-3)^2=9`