Question

URGENTE!!!!!

2-Achar as raízes das equações ​

Answer 1

Resposta:

a) S ={-4, 5}

b) S={-1, 4}

c) S={1, 7}

Explicação passo-a-passo:

a) x² - x -20=0

a=1

b=-1

c=-20

Δ = b² - 4 * a * c

Δ = (-1)² - 4 * 1 * -20

Δ = 1 + 80

Δ = 81

x = -b ± √Δ / 2 *a

x = -(-1) ±√81 / 2 * 1

x1 = 1 + 9 / 2

x1 = 10 /2

x1 = 5

x2 = 1 - 9 / 2

x2  = -8 / 2

x2 = -4

b) x² - 3x -4 = 0

a=1

b=-3

c=-4

Δ = b² - 4 * a * c

Δ = (-3)² - 4 * 1 * - 4

Δ= 9 + 16

Δ = 25

x = -b ± √Δ / 2 *a

x = -(-3) ±√25 / 2 * 1

x1 = 3 + 5 / 2

x1 = 8 / 2

x1 = 4

x2 = 3 - 5 / 2

x2 = -2 / 2

x2 = -1

c) x² - 8x + 7 = 0

a=1

b=-8

c=7

Δ = b² - 4 * a * c

Δ = (-8)² - 4 * 1 * 7

Δ= 64 - 28

Δ = 36

x = -b ± √Δ / 2 *a

x = -(-8) ±√36 / 2 * 1

x1 = 8 + 6 / 2

x1 = 14 / 2

x1 = 7

x2 = 8 - 6 / 2

x2 = 2 / 2

x2 = 1