Վ . 620

ա) 2x² = 5 +3x

2x² — 3x — 5 = 0

a = 2, b = -3, c = -5

D = b² — 4ac = 9 — 4 * 2 (-5) = 9 + 40 = 49

x₁ = -b — √D / 2a = 3 — 7 / 4 = -1

x₂ = -b + √D / 2a = 3 + 7 / 4 = 5/2

Պատ.` -1, 5/2 :

բ) -x² + 14x — 48 = 0

a = -1, b = 14, c = -48

D = b² — 4ac = 196 — 4 * (-1) — (-48) = 196 — 192 = 4

x₁ = -b — √D / 2a = -14 + 2 / -2 = -12/-2 = 6

x₂ = -b + √D / 2a = -14 -2 / -2 = -16/-2 = 8

Պատ.` 6, 8:

գ) — 7x² + 2x = -329

-7x² + 2x + 329 = 0

a = 7, b = 2, c = 329

D = b² — 4ac = 4 — 4 * (-7) * 329 = 9216

x₁ = -b — √D / 2a = -2 + 96 / -14 = — 94/14 = — 47/7 = -6 5/7

x₂ = -b + √D / 2a = -2 — 96 / -14 = 7

Պատ.` -6 5/7, 7:

Վ . 621

ա) x² + 6x + 8 = 0

a = 1, b = 6, c = 8

D = b² — 4ac = 36 — 32 = 4

x1 = -b — √D / 2a = -6 — 2 / 2 = -4

x₂ = -b + √D / 2a = -6 + 2 / 2 = -4/2 = -2

Պատ.` -4, -2: