1. ## polynomial division

the expression
f(x) = x^3 + ax^2 + bx + 10
is divisible by (x+2) but leaves a remainder of 12 when divided by (x+1)

a) Find the values of a and b
b) solve the equation f(x) = 0

i have done a) (i think) and come up with a = 4 b = -7 (is that right)

and im completely stumped on b)

any help is appericated

2. I get $a=-4\;\&\;b=-7$
Now you know that $(x+2)$ is one factor so $x=-2$ is one root.
Use that to find the other roots.

3. thank you

so x = -2, x = + 1 and x = + 5

just so i can see where i went wrong how did you geta = -4

thanks again

4. If a given polynomial expression f is divided by x-a, then the remainder is the number f(a).

Because the expression is divisible by (x+2), it has a remainder of 0.

Use these facts to solve for a and b.

5. Originally Posted by Chop Suey
If a given polynomial expression f is divided by x-a, then the remainder is the number f(a).
I just want to clarify that a in that instance is just an arbitrary number and not the one related to the question.