Hi, I was just doing some basic differentiation revision and came across this question. I’m stuck on part C. I understand the method but when solving for the x coordinate of Q using the negative reciprocal of P as the gradient, I get two solutions (one negative and one positive). The solution (lined paper scan) says x is positive and I can’t seem to understand why... I might be missing a simple concept like always. I tried to visualise the graph of the tangent at point P on C but didn’t get anywhere. Attached is my working in iPad handwriting, the solution (on lined paper) and the question. Thanks in advance.