Answer:
x = 3 or x = -3
Step-by-step explanation:
If x^2 - 9 = 0 we transfer 9 to the right side of the equation and it's change negative sign to positive while doing so
now we have x^2 = 9 the square of a number must be equal to a positive number in real numbers
but the root can be either negative or positive so we say x = 3 or x = -3
