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

4 Answers
Oct 3, 2017

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

Oct 3, 2017

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]

Oct 3, 2017

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.

Oct 3, 2017

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