652-655

x₁ + x₂ = 10

x₁ * x₂ = 21

x₂ — 10x + 21 = 0

D = 100 — 84 = 16

X₁ = 10 + 4 / 2 = 7
X₂ = 10 — 4 / 2 = 3

x₁ + x₂ = 14

x₁ * x₂ = 36,75

x₂ — 14x + 36,75 = 0

D = 196 — 147 = 49

X₁ = 14 + 7 / 2 = 10,5
X₂ = 14 — 7/ 2 = 3,5

ա)

x * (x + 1) = 110

x² + x = 110

x² + x — 110 = 0

D = 1 + 440 = 441

X₁ = -1 + 21 / 2 = 10

10 * 11 = 110

բ)

x * (x + 1) = 210

x² + x = 210

x² + x — 210 = 0

D = 1 + 840 = 841

X₁ = -1 + 29 / 2 = 14

14 * 15 = 210

գ)

x * (x + 7) = 44

x² + 7x = 44

x² + 7x — 44 = 0

D = 49 + 176 = 225

X₁ = -7 + 15 / 2 = 4

4 + 7 = 11
4 * 11 = 44

դ)

x * (x — 12) = 448

x² — 12x = 448

x² — 12x — 448 = 0

D = 144 + 1792 = 1936

X₁ = 12 + 44 / 2 = 28

28 — 12 = 16
28 * 16 = 448

ա)

x + y = 20

x² + y² = 218

x = 20 — y

(20 — y)² + y² = 218

400 — 40y + y² + y² = 218

400 + 2y² — 40y = 218

400 + 2y² — 40y — 218 = 0

2y² — 40y + 182 = 0

y² — 20y + 91 = 0

D = 400 — 364 = 36

X₁ = 20 + 6 / 2 = 13
X₂ = 20 — 6/ 2 = 7

բ