How do u solve this:
square root of 6x-9 equals x

first we are going to get rid of the square root by raising both sides to the power of 2

6x - 9 = x²
x² - 6x + 9 = 0

now the equation is a quadratic, and you can solve for x 

i'm going to factor it, but there are many ways to solve for a quadratic
(x - 3)(x - 3) = 0
If you FOIL this, it becomes x² - 6x + 9 

(x - 3)² = 0
x - 3 = 0
x = 3

to check the answer, you can plug 3 back into the original equation