QUOTE(Betinho @ Mar 16 2006, 08:06 PM)

QUOTE(Dave @ Mar 16 2006, 07:31 PM)

the line you dont understand comes about because there is a common factor of X in there. This makes sense as a quadratic is in the form Ax^{2}+bx + c. noteing that p is just a number so -8p-1 is a constant

and b = -(8p+4)

Ah, yeah, silly me. I wrote it down correct when I was doing the calculation but typed it out wrong.

Anyhoo, I got: p = -20/8 and p = -4 for some reason.

Er, what did I do wrong this time?

I put *** where I think you went wrong - well this line is still correct but it the line following it is wrong. Keep the 64p^2 + 96p + 20 equal to zero, take out a common factor of four to get 4(16p^2 + 96p + 20) = 0. Now you have to split the part inside the bracket into two different brackets, and then find the values for p which make the brackets, and therefore the whole thing, equal to zero. One of them should be greater than -1.