How do you solve 7x^2-6=577x2−6=57?

4 Answers
EZ as pi
Oct 3, 2017

x=+3 orx =-3x=+3orx=−3

Explanation:

There is no term in xx, so you can solve for x^2x2

7x^2 = 57+6" "larr7x2=57+6 ← add 6 to both sides.

7x^2 = 63" "larr div 77x2=63 ←÷7

x^2 =9x2=9

x= +-sqrt9x=±√9

x =+-3x=±3

Binayaka C.
Oct 3, 2017

Solution: x=3 , x = -3x=3,x=−3

Explanation:

7x^2 -6 = 57 or 7x^2 =57+6 or 7x^2 =637x2−6=57or7x2=57+6or7x2=63 or

x^2 =63/7 or x^2 =9 or x = +- sqrt 9 or x = +-3x2=637orx2=9orx=±√9orx=±3

Solution: x=3 , x = -3x=3,x=−3 [Ans]

MysticSmile
Oct 3, 2017

x=3x=3 or x=-3x=−3

Explanation:

First, we add 66 to both sides.
7x^2-6=577x2−6=57
7x^2-6color(blue)+color(blue)6=57color(blue)+color(blue)67x2−6+6=57+6
Simplify:
7x^2=637x2=63

Divide both sides by 77

(7x^2)/7=63/77x27=637

Therefore, x^2=9x2=9

If x^2=ax2=a, then x=sqrtax=√a or -sqrta−√a.

9=3^29=32
x=sqrt(3^2)x=√32
x=3x=3

or

x=-sqrt9x=−√9
x=-sqrt(3^2)x=−√32
x=-3x=−3

Both ways work.

Alan P.
Oct 3, 2017

x=+-3x=±3

Explanation:

If
color(white)("XXX")7x^2-6=57XXX7x2−6=57
then
color(white)("XXX")7x^2=63XXX7x2=63 ...after adding 66 to both sides
and
color(white)("XXX")x^2=9XXXx2=9 ...after dividing both sides by 77

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

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