Respuesta :

#13:

s² = 144
√(s²) = √144
|s| = 12

s = -12 OR s = 12

--------------------

#15 (not sure what letter you used so I went with 'g')

(g-6)² = 25
√[(g-6)²] = √25
|g-6| = 5

g - 6 = -5 OR g - 6 = 5

g = 1 OR g = 11