Question

EQUAÇÕES:
A)x²-x-2=0
B)x²-6x+5=0
C)x²-8x+15=0
D)x²-10x-11=0

Answer 1

A) x²-x-2=0

a = 1 ; b = -1; c = - 2 

▲ = b^2 - 4a*c = (-1)^2 -4(1)(-2) = 9

x = (-b ±√▲): 2 

x = (1 ± 3) : 2

x1 = 4/2 = 2 ;
x2 = -2/2 = -1

S = {-1,2}

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B) x²-6x+5 = 0

a = 1 ; b = -6 ; c = 5

▲ = b^2 - 4a*c 

▲ = 16 

x = (-b ±√▲): 2 

x = (6 ± 4) : 2 

x1 = 10:2 = 5
x2 = 2:2 = 1 

S = {1,5}

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C) x²-8x+15=0

a = 1 ; b = -8 ; c = 15

▲ = b^2 - 4a*c 

▲ = 4

x = (-b ±√▲): 2 

x = (8 ± 2) : 2 

x1 = 10 : 2 = 5
x2 = 6 : 2 = 3 

S = {3,5}

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D) x²-10x-11=0

a = 1 ; b = -10 ; c = -11

▲ = b^2 - 4a*c 

▲ = 144

x = (-b ±√▲): 2 

x = (10 ± 12) : 2 

x1 = 22 : 2 = 11
x2 = -2 : 2 = -1 

S = {-1,11}


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15/09/2016
Sepauto 
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