If f(x) = k(x - k) and k is a constant, what is the value of f(8) - f(3), in terms of k?
Choose the correct answer
A) 1
B) 5k
C) 7k - 1
D) k^2 + k
E) k^2 - k
First, distribute f(x). k(x - k) = kx - k^2. Now evaluate f(8) and f(3):   f(8) = k(8) - k^2 = 8k - k^2   f(3) = 3k - k^2   Answer 5k
<result>B</result>
If f(x) = k(x - k) and k is a constant, what is the value of f(8) - f(3), in terms of k?