jmc

Question

The function f is linear and satisfies f(d+1)-f(d) = 3 for all real numbers d. What is f(3)-f(5)?

Accepted Answer

Taking d = 3, we get f(4) - f(3) = 3.Taking d = 4, we get f(5) - f(4) = 3.Adding these equations, we get f(5) - f(3) = 6, so f(3) - f(5) = -6.