If f(x)=2x2+kf(x) = 2x^2 + kf(x)=2x2+k, where kkk is a constant, what is f′(x)f'(x)f′(x)?
4x+k4x + k4x+k
4x4x4x
4x+14x + 14x+1
2x2x2x