SOLUTION: solve the equation by completing the square. {{{c^2+4c-7=0}}}. my answer was {{{(-2)+-sqrt(11)}}}. am i correct?

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: solve the equation by completing the square. {{{c^2+4c-7=0}}}. my answer was {{{(-2)+-sqrt(11)}}}. am i correct?      Log On


   

Question 124354: solve the equation by completing the square. c%5E2%2B4c-7=0. my answer was %28-2%29%2B-sqrt%2811%29. am i correct?
Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
solve the equation by completing the square. c%5E2%2B4c-7=0. my answer was %28-2%29%2B-sqrt%2811%29. am i correct? 

That's what I got!

Do you have a TI graphing calulator?  If you have 
one you can check your own problems with it easily, 
like this:

On the main screen type either one of your two answers: 

type -2+Ö(11) then press 
these keys: 

STO

XTqn

ENTER

type X²+4X-7 then press:

ENTER

You get the right side of the original equation,
which is 0, so the answer is correct.

Takes a while to get used to checking algebra with a 
graphical calculator, but you get fast at it.

Edwin