algebra problem I'm stuck on

**mathgeek777** · August 20th 2008, 12:12 PM

$\sqrt{\sqrt{x+5}+x}=5$

$\sqrt{x+5} + x = 25$

$(\sqrt{x+5})^2 = (25-x)^2$

$x+5 = 625 - 50x - x^2$

$0 = \frac{-x^2 = 49x + 620}{-1}$

$0 = x^2 + 49x - 620$

Plug that into the quadratic equation and I get:

x = $\frac{-49 \pm \sqrt{4881}}{2}$

Which I can't find a way to simplify down.

The book shows the answer to be 21. How they got it, I have no idea. So any help will be greatly appreciated

**Chris L T521** · August 20th 2008, 12:20 PM

Originally Posted by mathgeek777

$\sqrt{\sqrt{x+5}+x}=5$

$\sqrt{x+5} + x = 25$

$(\sqrt{x+5})^2 = (25-x)^2$

$x+5 = 625 - 50x {\color{red}+} x^2$

...

From here, you should get $x^2-51x+620=0$

When solved you should get $x=31$ or $x=20$ . I'll let you test these values. Only one is correct.

The book answer is incorrect. 21 is not a possible solution for x.

--Chris

**mathgeek777** · August 20th 2008, 12:44 PM

Its amazing how i seem to miss the tiniest details....

Thanks for the help

Thread: algebra problem I'm stuck on

LinkBack

Thread Tools

Display

algebra problem I'm stuck on

Similar Math Help Forum Discussions

Stuck on Algebra in an Integral

IM stuck on algebra!

Stuck - Algebra 2

[SOLVED] Stuck in Algebra

calc II, but stuck on algebra

Search Tags