Hi everybody! I've hit a blank with regards to this 1 equation on a old exam paper - think I've overloaded myself a bit and just feel a bit like a airhead at the moment! I understand the actual method and getting to the answer but it starts off with a equation which you then need to get to a standard form to use the formula to check if the roots are rational. The initial equation is this : 4x^2 + 2kx - k = 2x Then on the memorandum this is taken to standard form so the info can be substituted into the formula Δ = b^2 - 4ac the standard form they then write that initial equation in is : 4x^2 + 2(k-1)x-k = 0 How do they get from 4x^2 + 2kx - k = 2x to this 4x^2 + 2(k-1)x-k = 0 The rest I understand entirely. Literally just the above has be scratching my head! Please help :) Thank you!