The function f is defined on all the reals such that f (ac) = x2 + kx - 3 for x 1 3x + b for x > 1 Find the value of k and b if f is a differentiable function on its entire domain. O k =1, b=3 O k = -1, b= -3 O k =4, b=1 O k =1, b=4