Very interesting. Never seen this before lol.
In other words, if a rectangle is 10 cm by 15 cm, what is the length of the diagonal? Use the Pythagorean Theorem. a^2+b^2=c^2, where c is the measure of the hypotenuse.
Given:
Consider the given equation is

To find:
The values of x.
Solution:
We have,

Taking square root on both sides, we get


Adding 18 on both sides, we get


Now,
and 
and 
Therefore, the correct option is A.