Find the gradient of the tangent on the curve at the point (4, ). Express your answer as a rational number.
The textbook's answer is whilst I keep getting . Is the textbook right?
If the equation of the curve is then you are right - assuming that you mean the point . But you can't express the answer as a rational number. The best you can do is what you have done: express the answer with a rational denominator.
But are you sure you've read the question properly?