Expert: Richard J. Raridon - 8/5/2004

Question
Hi,Richard.
Can you help me with this "complete the square" problem?
x^2-3x-7=0


Answer
re-write it as x^2 -3x = 7
It has to be of the form (x-a)^2 which equals x^2 -2a +a^2
so -2a = -3x and x = 2/3 and x^2 = 4/9
Therefore, you add 4/9 to each side to get
x^2 -3x +4/9 = 7+4/9 = 67/9
and (x -2/3)^2 = 67/9
x -2/3 = +/- (67^1/2)/3
x = 2/3 +/- (67^1/2)/3