Resposta:

Bom diaa!

1°)

a) x² - 8x - 20 = 0

Δ = (-8)² - 4 × 1 × (-20)

Δ = 64 + 80

Δ = 144

x = -(-8) + - √144 / 2 × 1

x = 8 + - 12 / 2

x¹ = 10 x² = -2

S = x¹ + x² = 8

P = x¹ × x² = -20

b) 2x² - 20x + 10 = 0

S = -b/ a

S = 10

P = c/a

P = 5

c) 3x² + 15x + 30 = 0

S = -5

P = 10

2°)

a) 3x² - 15x = 0

x ( 3x - 15 ) = 0

3x = 15

x = 5

S = { 0 , 5 }

b) 2x² + 8x = 0

x ( 2x + 8 ) = 0

2x = -8

x = -4

c) x² - 49 = 0

x² = 49

x = 7

d) x² - 16 = 0

x² = 16

x = 4

3°)

a) x² + 6x + 5 = 0

Δ = 6² - 4 × 1 × 5

Δ = 36 - 20

Δ = 16

b) x² + 10x + 7 = 0

Δ = 10² - 4 × 1 × 7

Δ = 100 - 28

Δ = 72

c) 3x² + 5x - 7 = 0

Δ = 5² - 4 × 3 × (-7)

Δ = 25 + 84

Δ = 109

d) x² + 7x + 10 = 0

Δ = 7² - 4 × 1 × 10

Δ = 49 - 40

Δ = 9

espero ter ajudado ☆