1)

x² = 225

x = ±

x = ± 15

x = 15

x = -15

Ответ: x = 15, -15

2)

24 + y² = 25

y² = 25 - 24

y² = 1

y = ±

y = ±1

y = 1

y = -1

Ответ: y = 1, -1

3)

Ответ: x = 361