# Math Help - Help on this quadratic problem

1. ## Help on this quadratic problem

Let f(x) = x^2 - 2x. Let e be a real between -1< e < 15. Find a c where 1 < c < 5 such that f(c) = e.

Thanks

2. Originally Posted by storchfire1X
Let f(x) = x^2 - 2x. Let e be a real between -1< e < 15. Find a c where 1 < c < 5 such that f(c) = e.

Thanks
C=2

3. Double post. Sorry.

4. It seems to me that $f1,5) \to (-1,15)" alt="f1,5) \to (-1,15)" />

5. Perhaps the original post has been changed but I don't see how either of those really helps. If c= 2, then f(c)= f(2)= 4- 4= 0 but the problem said "let e be any number between -1 and 15 and find c such that f(c)= e". Yes, f maps (1, 5) to (-1, 15) which means there is a solution.

storchfire1X, the equation $f(x)= x^2- 2x= e$ is the same as the quadratic equation $x^2- 2x- e= 0$. You can use the quadratic formula to solve it. The quadratic formula will give two roots for the equation but only one of them will be between 1 and 5
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