SOLUTION: apply the quadratic formula to find the roots of the given function, and then graph the function. 0 = x² - 9

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: apply the quadratic formula to find the roots of the given function, and then graph the function. 0 = x² - 9      Log On


   



Question 601283: apply the quadratic formula to find the roots of the given function, and then graph the function.
0 = x² - 9

Answer by Edwin McCravy(20055) About Me  (Show Source):
You can put this solution on YOUR website!
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

x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+

x+=+%28-%280%29+%2B-+sqrt%28+%280%29%5E2-4%2A%281%29%2A%28-9%29+%29%29%2F%282%2A%281%29%29+

x+=+%28%22%22+%2B-+sqrt%28-4%2A%281%29%2A%28-9%29+%29%29%2F%282%29+

x+=+%28%22%22+%2B-+sqrt%28%22%22%2B36%29%29%2F%282%29+
 
x+=+%22%22+%2B-+%286%29%2F%282%29+

x+=+%22%22+%2B-+3

Edwin