
Algebra PreAlgebra and Basic Algebra Math Forum 
 LinkBack  Thread Tools  Display Modes 
August 7th, 2009, 08:56 AM  #1 
Newbie Joined: Aug 2009 Posts: 1 Thanks: 0  help with a no solution
Studying up for a placement exam this fall to get back into calc one from which I had to withdraw two years ago. So far almost everything is coming back, but there are a few sticking points. This one is is 'no solution' in the answer key, and though I can come up with some crazy answers, they are still solutions. Could someone tell me what I'm missing? f(x)=(sqrt(52x))(x/2) find all input(s), x, suth that f(x)=2 
August 7th, 2009, 12:07 PM  #2 
Global Moderator Joined: Dec 2006 Posts: 20,485 Thanks: 2041 
There is no real solution. The first term on the righthand side is nonnegative by definition, and so the minimum value of the righthandside is 5/4, occurring when x = 5/2. If you check what you did, it's almost certainly the case that you introduced extraneous solutions.

August 7th, 2009, 12:15 PM  #3  
Senior Member Joined: Mar 2009 Posts: 318 Thanks: 0  Quote:
[color=white]. . . . .[/color]2 = sqrt[5  2x]  x/2 [color=white]. . . . .[/color]4 = 2sqrt[5  2x]  x [color=white]. . . . .[/color]x  4 = 2sqrt[5  2x] [color=white]. . . . .[/color]x^2  8x + 16 = 4(5  2x) [color=white]. . . . .[/color]x^2  8x + 16 = 20  8x [color=white]. . . . .[/color]x^2  4 = 0 Solve the quadratic in the last line above for its two solution values. Then remember to check them in the original equation, to see which, if either, works there.  

Tags 
solution 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Why my solution is different from sample solution?  rain  Real Analysis  1  July 17th, 2013 12:28 PM 
my correct solution but another solution?  davedave  Calculus  1  January 31st, 2012 02:48 PM 
need help and solution  ranna  Advanced Statistics  0  May 29th, 2011 02:48 AM 
Need solution of following eqn.  bdcrown007  Calculus  1  January 26th, 2011 07:27 PM 
trying to make a solution (liquid solution...) problem...  TreeTruffle  Algebra  2  March 27th, 2010 01:22 AM 