Question

помагите задание на фото​

Answer 1

1) x² + 7x – 18 = 0

a = 1, b = 7, c = –18

D = 7² – 4·1·(–18) = 49 + 72 = 121 > 0, два корня

x₁ = (–7 – √121) / 2·1 = (–7 – 11) / 2 = –9

x₂ = (–7 + √121) / 2·1 = (–7 + 11) / 2 = 2

Ответ: –9; 2.

2) 2x² – 9x – 5 = 0

a = 2, b = –9, c = –5

D = (–9)² – 4·2·(–5) = 81 + 40 = 121 > 0, два корня

x₁ = (9 – √121) / 2·2 = (9 – 11) / 4 = –1/2

x₂ = (9 + √121) / 2·2 = (9 + 11) / 4 = 5

Ответ: –1/2; 5.