I'm having problems getting started on this question. I think once this parts cracked I can continue with the other parts.

The 1st, 2nd & 3rd terms of an AP are p , q & p^2 resepctively, where p is negative.

The 1st, 2nd & 3rd terms of a GP are p , p^2 & q resectively.

Show that p = -1/2 and find the value of q.

So, as this is an AP I know that U_2 - U_1 = U_3 - U_2 = d

Therefore, (q - (-p)) = (p^2 - q)

rearrange and I get q = (p^2 - p)/2 = d

I try subbing this in for U_2: a + 2d = q

as I have just found q and d to be (p^2 - p)/2

I dont end up with -1/2 though. Am I approaching this completely wrong or have I made a schoolboy error.

Your help is much appreciated - I have a test tomorrow!!!

thanks, D