в) −5x² + 45 = 0
−5x² = −45
x² = 9
x = ±√9
x = ±3
г) −9x² + 13 = 0
−9x² = −13
x² = 13/9
x = ±√(13/9)
x = ±(√13)/3
Ответ: в) x = 3, x = -3; г) x = (√13)/3, x = -(√13)/3