SOLUTION: sove quadratic equation by taking square root. sove (2x+2)^2 = 64 I have done: 4x^2 + 4 = 64 4x^2=60 divide by 4 x^2=60/4 x=sqrt 15 AM I DOING THIS RIGHT?

Algebra ->  Inequalities -> SOLUTION: sove quadratic equation by taking square root. sove (2x+2)^2 = 64 I have done: 4x^2 + 4 = 64 4x^2=60 divide by 4 x^2=60/4 x=sqrt 15 AM I DOING THIS RIGHT?      Log On


   

Question 28505: sove quadratic equation by taking square root.
sove (2x+2)^2 = 64
I have done:
4x^2 + 4 = 64
4x^2=60
divide by 4
x^2=60/4
x=sqrt 15
AM I DOING THIS RIGHT?
Found 2 solutions by LilSkittleMd, bmauger:
Answer by LilSkittleMd(119) About Me  (Show Source):
You can put this solution on YOUR website!
%282x%2B2%29%5E2 = 64
The first thing you do is square root both sides of the equation. This will cancel out the %5E2 and will give you %2B%2F-8

Answer by bmauger(101) About Me  (Show Source):
You can put this solution on YOUR website!
%282x%2B2%29%5E2+=+64+
Not quite...
Remember, squaring a binomial isn't the same as squaring each term.
%282x%2B2%29%5E2%3C%3E4x%5E2%2B4 it's actually the same as multiplying the two terms together:
%282x%2B2%29%5E2=%282x%2B2%29%282x%2B2%29=4x%5E2%2B8x%2B4
Anyway, that's not getting you any closer to the answer, the correct way to approach this problem is to take the square root of both sides.
%282x%2B2%29%5E2=64
When you take the square root, you have to remember that you'll actually have two equations, because 2x+2 could be -8 or 8 and either way when you square it you'll get 64, so we write:
2x%2B2=0%2B-+8 (ignore the 0, it's just to get the +- symbol to work in the equation editor)
Or you could write it as two equations 2x%2B2=8 and 2x%2B2=-8
When you subtract 2 from both sides you get:
2x=-2%2B-+8 Divide by 2:
x=-1%2B-+4
So your answers are x=-1%2B4=3 and x=-1-4=5
x=3, -5
Graphically (green = (2x+2)^2 & red = 64) crosses at x=3 and x=-5:
graph%28300%2C+300%2C+-10%2C+10%2C+-10%2C+80%2C+64%2C+%282x%2B2%29%5E2%29