Well the equation is (A^2)+(B^2)=(C^2)
A= x
B= 2x
C will always be the longest side because it is the Hypotenuse = 25
So if you plug in those numbers into the equation...
(x^2) + (2x^2) = (25^2)
x^2 + 4x^2 = 625
Combine like terms
5x^2 = 625
Divide by five to both sides
x^2 = 125
Then Square root,
x = sqrt(125)
x = sqrt(25* 5)
x = 5sqrt(5)
