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Mon 27 May, 2013 01:07 pm
My homework for Algebra 1 involves completing the square. For one of the first few problems, I decided to check my work in the "selected answers" bit at the back of the book. The problem was x^2+14x=13
the book says that the answers were 13 and 1, yet I always end up with the Square root of 62 plus 7. I AM SO CONFUSED! Please help. They expect us to get rational solutions to imperfect squares.
@jaxond99,
You are close if that is the original problem.
x^2 + 14x = 13
x^2 + 14x + 49 = 13 + 49 ==> since (14/2)^2 = 49
(x +7)^2 = 62
x = +or- sqrt(62) - 7
x = .874 and -14.874
But check to make sure you have the original problem correct.
If:
x^2 + 14x = -13
Then:
x = -13 and -1.
@tomr,
OOOHHHHHHH!!!! I had the problem wrong. Thank you so much!
@jaxond99,
Solution: Given x²+14x=13
if you want the answer as 13 and 1
then your question is wrong
the equation should be
x²-14x=-13
x²-14x+13=0
x²-13x-x+13=0
x(x-13)-1(x-13)=0
(x-13)(x-1)=0
x=13
x=1
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