The Chain Rule. mc-TY-chain A special rule, thechainrule, exists for diﬀerentiating a function of another function. This unit illustrates this rule. In order to master the techniques explained here it is vital that you undertake plenty of practice exercises so that they become second nature. •In calculus, the chain rule is a formula for computing the derivative of the composition of two or more functions. That is, if f is a function and g is a function, then the chain rule expresses the derivative of the composite function f ∘ g in terms of the derivatives of f and g. Definition. Exponent and Logarithmic - Chain Rules a,b are constants. Function Derivative y = ex dy dx = ex Exponential Function Rule y = ln(x) dy dx = 1 x Logarithmic Function Rule y = a·eu dy dx = a·eu · du dx Chain-Exponent Rule y = a·ln(u) dy dx = a u · du dx Chain-Log Rule Ex3a. Find the derivative of y = 6e7x+22 Answer: y0 = 42e7x+22 a = 6 u.