Joseph is considering the function f: R R defined by f(x) = x + 5x+7. Joseph wants to know if f is invertible. Explain why f must have an inverse function f-1 (b) Joseph's favourite number is 13. Help them find the value of f-1(13) by inspection. f-(13) = Number Hence also help Joseph find the value of f(13) da f-(13) = dz (c) Let g: R R be a continuous function such that fax + 5x Number g(t) dt = -2x Help Joseph find the value of g(13) by differentiating the above equation with respect to g (13) = Number