Calculus..Need Help Soon
posted by Leanna on .
If x=1 and x=2 are zeros of f(x)=3X^3+Ax^2+Bx+2, then the value of A+B is a)1, b)1, c)9, d)9, e) cannot be determined
I think it can't be determined but i don't know!

Find A+B in
f(x)=3X^3+Ax^2+Bx+2,
Hints:
1. two of the roots are 1 and 2, then two of the factors are (x1) and (x2)
2. the third root must be of the form
(3x±1) to satisfy the coefficient 3x^3 and the constant term.
3. Determine the sign of the factor in (2).
4. Expand
(x1)(x2)(3x±1)
to find A and B, and hence A+B.