Use the Pythagorean theorem:

Answer:
The solution is x =2 for the given equation 
Step-by-step explanation:
We need to find the solution for x in the given equation.

Solving:
Subtract
from both sides

Taking square on both sides

Putting values and solving

Verifying the solution by putting values of x in given equation
Putting x=18

So, x=18 is not solution o given equation.
Putting x = 2

So, x=2 satisfies the equation
The solution is x =2 for the given equation 