If u, v and w are functions of x, then show that
`d/dx(u.v.w) = (du)/dx v.w+u. (dv)/dx.w + u.v. (dw)/dx`
in two ways-first by repeated application of product rule, second by logarithmic differentiation.
Find the derivative of the function given by f (x) = (1 + x) (1 + x2) (1 + x4) (1 + x8) and hence find f ′(1).