SOLUTION: How do you find equations for polynomials when only given their graphs??

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Question 77691: How do you find equations for polynomials when only given their graphs??
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
You can approximate the equation by looking at its roots

For instance, this graph

+graph%28+300%2C+200%2C+-6%2C+5%2C+-10%2C+10%2C+%28x%2B5%29%28x-3%29%29+

has roots of x=-5 and x=3. So for any root of x=a, the factor will be

x-a=0. So if we have roots of x=a and x=b, then our factorization is:
%28x-a%29%28x-b%29=0
So this means our factorization is %28x%2B5%29%28x-3%29 since we have roots of x=-5 and x=3
Now we just foil %28x%2B5%29%28x-3%29 to get x%5E2%2B2x-15. This doesn't work all the time since we might have a stretch or compression factor.