Find the Inverse

(x)=√2x+9

I'm going to assume that the only thing under the square root symbol is the 2.

Write your equation with a "y" on the left side:
y = √2x+9

And then to find the inverse, you first just switch the x's and the y's, and get,
x = √2y+9

And then you solve this for y,
Flip it around,
√2y+9 = x
Move the 9 over to the right side,
√2y = x - 9
Divide both sides by √2, which will just leave a y on the left side,
y = (x - 9)/√2