An exponential function is a function of the form f ( x ) = c a x 𝑓 𝑥 𝑐 superscript 𝑎 𝑥 f(x)=ca^{x} , for c > 1 , a > 1 formulae-sequence 𝑐 1 𝑎 1 c>1,a>1 a constant.