The monomial 36x4 is a perfect square. what is the square root of 36x4?

6x2
6x4
18x2
18x4

I'm assuming the numbers after 'x' are powers (like x to the power of 2; x-squared;x^2). Anyway, the best answer to the question stated above would be 6x^2 (or the first choice). This is because the square root of 36 is 6 and the square root of x^4 is x^2. I hope this helps.