Answer:
f(x) = 7/(x+3) -38/(x+3)²
Explanation:
The denominator is a perfect square, so the decomposition to fractions will involve both a linear denominator and a quadratic denominator.
You can start with the form ...
... f(x) = B/(x+3) + A/(x+3)²
and write this sum as ...
... f(x) = (Bx +3B +A)/(x+3)²
Equating coefficients gives ...
... Bx = 7x . . . . . B = 7
... 3B +A = -17 . . . . the constant term
... 21 +A = -17 . . . . filling in the value of B
... A = -38 . . . . . . . subtract 21 to find A
Now, we know ...
... f(x) = 7/(x+3) -38/(x+3)²