Question

B ) 4x² - 25=0

C) 3x²-9=0

D) 2x²+8x=0

E) x²-5x=0

F) 3x²-12x=0

Usando equação de 2°grau incompleta !!!!

Answer 1

4x² - 25 = 0
4x² = 25
x² = 25/4
x = raiz de 25 = 5 e raiz de 4 = 2
x = 5/2
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c) 3x² - 9 = 0 
3x² = 9
x² = 9/3
x² = 3
x = $\sqrt{3}$
x = $-\sqrt{3}$

d) 2x² + 8x = 0
2x(x + 4) = 0
2x = 0
x = 0/2
x = 0

x + 4 = 0
x = -4

e) x² - 5x = 0 
x(x - 5) = 0
x = 0

x - 5 = 0
x = 5

f) 3x² - 12x = 0 
3x(x - 4) = 0
3x = 0
x = 0/3
x = 0

x - 4 = 0
x = 4

BONS ESTUDOS

c) 6x² + 11x + 4 = 0
Delta = b² - 4ac
Delta = (11)² - 4(6)(4)
Delta = 121 - 96
Delta = 25
X = (-b +- raiz delta) / 2a
X = (-11 +- 25) / 12
x' = (-11 + 5) / 12 = -6/12 = -1/2
x" = (-11 - 5) / 12 = -16/12 = -4/3

d) 3x² + 4x + 1 = 0
Delta = b² - 4ac
Delta = (4)² - 4(3)(1)
Delta = 16 - 12
Delta = 4
X = (-b +- raiz delta) / 2a
X = (-4 +- 4) / 6
x' = (-4 + 2) / 6 = -2/6 = -1/3
x" = (-4 - 2) / 6 = -6/6 = -1

e) x² - 7x + 2 = 0 
Delta = b² - 4ac
Delta = (-7)² - 4(1)(2)
Delta = 49 - 8
Delta = 41
Raiz Delta inexata!

x² - 7x + 2 = 0
x(x - 7) + 2 = 0
x + 2 = 0
x = -2
x - 7 = 0
x = 7

f) x² + 10x + 15 = 0
Delta = b² - 4ac
Delta = (10)² - 4(1)(15)
Delta = 100 - 60
Delta = 40
Raiz Delta inexata!

x² + 10x + 15 = 0
x(x + 10) + 15 = 0
x + 15 = 0
x = -15
x + 10 = 0
x = -10

BONS ESTUDOS