Question

When f(x) = x^3 - 4x^2 + ax + b is divided by (x+3), the remainder is -64. (x-5) is a factor of f(x). Find the values of a and b. HEEELP PLEASE!

Answer 1

\[
\frac {x^3 - 4x^2 + ax + b}{ x+3}=21 + a - 7 x + x^2+ \frac {-63 - 3 a + b}{ x+3}\\
-64 = -63 - 3 a + b\\
3a -b =1
\]
Try to find another relation between a and b

Answer 2

\[ f(5)=0\\ 25 + 5 a + b =0\\ 5 a + b = -25 \]

Answer 3

Solve for a and b and you find
a = -3, b = -10

Answer 4

wait :o

Answer 5

nm ....

Answer 6

Your polynomial is
\[
f(x) = x^3-4 x^2-3 x-10
\]

Answer 7

OHHHH ok I see :D thank you so much! I have trouble with long division polynomials -_-

Answer 8

yw