Normally you would not use the quadratic formula on such a simple
propblem, but your teacher wants you to realize that the quadratic
formula works on even the simplest problems:


0 = x² - 9

Insert a place-holder term, + 0x: 

0 = x² + 0x - 9

Switch sides:

x² + 0x - 9 = 0

Give the x² a 1 coefficient:

1x² + 0x - 9 = 0

Compare that to

ax² + bx + c = 0

and get a=1, b=0, and c = -9








 




Edwin