Solving for all real values of x?

Question

I have a summer math packet and so far i have no clue what I'm doing. I just cant seem to remember how to do anything. I have to solve a bunch of problems for x and i don't remember how. Here is one of the problems:

x^2-9x+9=0

My brother said i have to use the quadratic formula but i don't remember how to use it. Can someone please help me i have a lot of problems left...

Answer 1

if we have an equation like this : ax^2+bx+c=0 , the answers come from the formula bellow :

x1 = ( -b + sqrt(b^2-4ac) )/ 2a  and x2= (-b-sqrt(b^2-4ac) )/2a

note that b^2- 4ac should be positive or zero for having real answers otherwise we have imaginary numbers for answer.

in this question the answer would be :

(9+sqrt(81-36) )/2 =(9+sqrt(45) )/2 and (9-sqrt(45) )/2