Respuesta :

4^2 + x^2 = (8 - x)^2
16 + x^2  = 64 - 16x + x^2 the two x^2 cancel out
16 = 64 - 16x
- 48 = - 16x
x = 3

check
4^2 + 3^2 = (8 - 3)^2
16 + 9 = 5^2
25= 25