Question 7 The formal definition of derivative of f (x) at x=a given as f '(a) = lim flat h)- f(a) h-0 h (a) Use the formal definition of the derivative to compute f '(1) when f(x) = (x+1) . (b) Then obtain an equation of the tangent line to the graph of f(x) = (x+1) at x =1. [4 marks]