April 8th, 2014, 04:46 PM  #1 
Newbie Joined: Apr 2014 From: california Posts: 2 Thanks: 0  4(x^2+4)=9+12x
^ is a power sign so x^2 is x squared 4(x^2+4)=9+12x 4x^2+16=9+12x 4x^212x+7=0 divide all by 4 x^23x+7/4=0 i am stuck here the answer sheet says this is the answer 3 +or √2 2 
April 8th, 2014, 05:16 PM  #2 
Senior Member Joined: Dec 2013 From: Russia Posts: 327 Thanks: 108 
Use the quadratic formula.

April 8th, 2014, 08:32 PM  #3 
Newbie Joined: Apr 2014 From: california Posts: 2 Thanks: 0 
So using that formula it eventually gets to 12+or 4√2 8 then if thats correct how do you continue to get? 3+or √2 2 
April 8th, 2014, 08:35 PM  #4 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs 
Factor a 4 from the numerator, and then cancel or divide out common factors: $\displaystyle \frac{12\pm4\sqrt{2}}{8}= \frac{\cancel{4}\left(3\pm\sqrt{2} \right)}{\cancel{4}\cdot2}= \frac{3\pm\sqrt{2}}{2}$ 