Respuesta :

√26+13 ² = (x+7)²
26x + 13 = X² +14X + 49
26X +13 - X² -14X - 49 = 0
12X - X² - 36 = 0
-(X²-12X+36) = 0
-(X-6)² = 0 
(X-6)² = 0 
X-6 = 0
X= 6