Find the polynomial function with roots 1,-2, and 5.I have looked over the problem 100 times and maybe it's just I overlook everything.

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Matthew Fonda | eNotes Employee

Posted on

We are looking for a polynomial with roots 1, -2, and 5. If we find functions with each of these as roots, and multiply them together, then the resulting function will have all three as roots. This leads us to the answer:

`f(x) = (x -1)(x + 2)(x - 5)`

If we multiply this out, we get

`f(x) = x^3 - 4x^2 - 7x + 10`

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islnds | (Level 1) Valedictorian

Posted on

Yes. Unless you can do it in your head :)

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jcjrjamsj | (Level 2) eNoter

Posted on

But okay when multiplying them together would you use FOIL on (x-1)(x+2)? And then multiply the answer for that with x-5?

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