Question

Exercícios

1) x2 – 9 = 0



2) x2 – 3x – 4 = 0



3) 2x2 – 5x = 0



4) x2 – 7x + 6 = 0



5) 9 (2n – 5) (n + 2) = 0



6) 5x2 +12x = 0



7) 2x2 – 3x + 1 = 0



8) y (y + 2) + (y – 1)2 = 9



9) x2 + 4x + 3 = 0



10) (t – 1)2 + (t + 2)2 – 9 = 0





ME AJUDEM, É URGENTEE

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Answer 1

Vamos lá :

1)

x² - 9 = 0

x² = 9

x = ±√9

x = ± 3

2)

x² - 3x - 4 = 0

S = -(- 3)/1 = + 3

P = - 4/1 = - 4

x₁ = - 1 ; x₂ = 4

3)

2x² - 5x = 0

x(2x - 5) = 0

x₁ = 0 ; x₂ = 5/2

4)

x² - 7x + 6 = 0

S = - (- 7)/1 = + 7

P = 6/1 = 6

x₁ = 1 ; x₂ = 6

5)

9(2n - 5)(n + 3) = 0

n₁ = - 3

9(2n - 5) = 0

2n - 5 = 0

n₂ = 5/2

6)

5x² + 12x = 0

x(5x + 12) = 0

x₁ = 0 ; x₂ = - 12/5

7)

2x² - 3x + 1 = 0

Δ = (- 3)² - 4.2.1 = + 9 - 8 = 1           >>√Δ = 1

x = (3 ± 1)/4

x₁ = (3 + 1)/4 = 4/4 = 1

x₂ = (3 - 1)/4 = 2/4 = 1/2

8)

y(y + 2) + (y - 1)² = 9

y² + 2y + y² - 2y + 1 = 9

y² + y² + 1 = 9

2y² = 9 - 1

2y² = 8

y² = 8/2

y = ±√4

y = ± 2

9)

x² + 4x + 3 = 0

S = - 4/1 = - 4

P = 3/1 = 3

x₁ = - 1 ; x₂ = - 3

10)

(t - 1)² + (t + 2)² - 9 = 0

t² - 2t + 1 + t² + 4t + 4 - 9 = 0

t² + t² - 2t + 4t + 1 + 4 - 9 = 0

2t² + 2t - 4 = 0  : 2

t² + t - 2 = 0

S = - 1/1 = - 1

P = - 2/1 = - 2

t₁ = - 2 ; t₂ = 1

Espero ter ajudado !!!