Question 880888
a^2 + b^2 = c^2
(x)^2 + (4x)^2 = (25)^2
x^2 + 16x^2 = 625
17x^2 = 625
divide each side by 17
x^2 = 625/17
 {{{x = sqrt(625/17)}}} or  {{{x = -sqrt(625/17)}}}
so
 {{{x = 25/sqrt(17)}}} or  {{{x = -25/sqrt(17)}}}