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Expert: Steve Holleran - 2/14/2008


Question
1. the quadratic equation x2 - 2x + k = 0 has solutions x=4 and x=-2. what is the value of k .

a. -8
b. -2
c. 1
d. 2
e. 8

Answer
Hi David,

An easy way to do this is to just substitute one of the solutions in for x:

   x=4 :  4^2 - 2(4) + k = 0

           16 - 8 + k = 0

                8 + k = 0 so k = -8.

You could have used -2 and gotten the same result.

Steve

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Steve Holleran

Expertise

I can help with all math questions from basic math to Calculus. Whether it`s consumer questions, or questions from high school or college students, I have probably dealt with it at some time in my career.

Experience

33 years teaching experience in NJ public schools

Education/Credentials
B.S. Mathematics : Wake Forest University 1972 M.S. Mathematics : Monmouth University 1981

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