Which of the following equations has only one solution?

x^2 = 9
x(x - 1) = 9
x^2 - 6x + 9 = 0

Jordan got 27 out of 90 correct on his test . what fraction of the marks did her get correct

Hurry if the population of of an ant hill doubles every 10 days and there are currently 100 ants living in the ant hill what will the ant population be in 20 days

(x-5)1/2+5=2 what is possible solution of this equation