If you have y^2-5y+1 and you need to subtract something from it to get 0, try it in parts. y^2-y^2=0, -5y+5y=0, 1-1=0. Remember that you are subtracting, so the y^2, the 5y, and the -1 you got are not the actual answers. Since the - in the parenthesis changes the signs, you need the remember to change the signs on the numbers you subtracted from the original numbers. So you get y^2. -5y, and 1. Put them together in a equation, and that's your answer.
