If they're saying that h prime is above the x-axis when x is greater than zero, then that would be a good answer, but this is just, you know, what is above the x-axis and over what interval? So, I would actually, let's scroll down a little bit. This looks like a good thing for the teacher to write. Please use more precise language. This cannot be accepted as a correct justification. And then finally, this last student wrote the derivative of h is positive when x is greater than zero, and it is indeed the case. If your derivative is positive, that means that your original function is going to be increasing over that interval.