What is the prime factorization of 81?

x = sqrt(45)

Step-by-step explanation:

We can use the Pythagorean theorem since this is a right triangle

a^2 + b^2 = c^2

where a and b are the legs and c is the hypotenuse

2^2 + x^2 = 7^2

4+x^2 = 49

Subtract 4 from each side

4-4+x^2 = 49-x

x^2 = 45

Take the square root of each side

sqrt(x^2) = sqrt(45)

x = sqrt(45)