Which of the following is a polynomial with roots 5, 7, and −8?

f(x) = x^3 − 35x^2 − 56x + 61

f(x) = x^3 − 35x^2 − 61x + 280

f(x) = x^3 − 4x^2 − 35x + 56

f(x) = x^3 − 4x^2 − 61x + 280

Question

Which of the following is a polynomial with roots 5, 7, and −8?

f(x) = x^3 − 35x^2 − 56x + 61

f(x) = x^3 − 35x^2 − 61x + 280

f(x) = x^3 − 4x^2 − 35x + 56

f(x) = x^3 − 4x^2 − 61x + 280

evoker · Answer

I would recommend multiplying the the three roots together so (x-5) (x-7) and (x+8)

mathstudent55 · Answer

You can also evaluate each function at 5, 7, and -8.
The function that gives you 0 for all those values of x is the one.

evoker · Answer

Good point and probably easier

mathstudent55 · Answer

@Megan_nicole86 
You have been told two methods.
If you have time, try them both.
It's good to learn how to solve problems in different ways because some methods are better for some problems, and some methods are better for other problems.

megan_nicole86 · Answer

Okay :) Thank you both of you! I'll do them both

mathstudent55 · Answer

yw