Question

If f(x) varies directly with x, and f(x) = 45 when x = 9, find the value of f(x) when x = 3

Answer 1

varies directly, means: \(f(x)=kx \) , where \(k\) is some constant. So you need to find this constant. Use the information you are given: \(45=k9\). From here you get \(k \)