## Simplifying Equation With Square Root

1. The problem statement, all variables and given/known data
An equation in a book lists this equation:
(c - 18)$$^{2}$$ = (-3$$\sqrt{c})$$$$^{2}$$

And it simplifies it as:
c$$^{2}$$ -45c + 324 = 0

2. The attempt at a solution
When I do out the equation, I get:
c$$^{2}$$ + 324 = 9 + c

i squared c, then -18 for the left side of the equation, then for the right side, I squared -3 to get 9, then $$\sqrt{c}$$, which is c.
 PhysOrg.com science news on PhysOrg.com >> King Richard III found in 'untidy lozenge-shaped grave'>> Google Drive sports new view and scan enhancements>> Researcher admits mistakes in stem cell study
 Blog Entries: 1 Recognitions: Gold Member Science Advisor Staff Emeritus Hi kwikness and welcome to PF, Firstly, note that; $$\left(a+b\right)^2 \neq a^2+b^2$$ Rather, $$\left(a+b\right)^2 = \left(a+b\right)\cdot\left(a+b\right) = a^2 +2ab + b^2$$ Secondly, $$(-3)^2 \neq 324$$ And thirdly; $$(a\cdot b)^2 \neq a^2+b^2$$ Rather, $$(a\cdot b)^2 = a^2\cdot b^2$$

 I squared -3 to get 324
Sorry, I meant 9 =)

I made my mistake when I forgot to "FOIL" the left-hand side of the equation. When I do so, I get:

C$$^{2}$$ -45c + 324 = 0

Thank you very much for clearing that up for me. I'm in a bit of a situation. I'm a good student in my 4th semester of college. In high school, I was able to slide by my math classes. I half-assed Algebra I, did okay in Geometry, and took no other math courses. Now I find myself in Calculus I, 5 years after my last math class. The first thing my professor said was, "You're not going to pass this course unless you've had Trigonometry and Pre-Calculus.", which I haven't. I'm now trying to backtrack and learn these courses myself with the aid of video tutorials and practicing problems on my own time. I excel in every subject at school but math. It's such a weakness for me and I'm now just starting to do something about it.

Any pointers are appreciated, thanks again for your help.