Answer:
sqrt(10) *x
Step-by-step explanation:
Since this is a right triangle, we can use the Pythagorean theorem
a^2 + b^2 = c^2
x^2 + (3x)^2 = hypotenuse ^2
x^2 + 9x^2 = hypotenuse ^2
10x^2 = hypotenuse ^2
Take the square root of each side
sqrt( 10x^2) = sqrt(hypotenuse ^2)
sqrt(10) * x = hypotenuse
