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Stella [2.4K]
3 years ago
8

O número -3 é a raíz da equação x² - 7x - 2c = 0. Nessas condições, determine o valor do coeficiente c: A) 7 B) -2 C) -3 D) 15 E

) NDA
Mathematics
1 answer:
Free_Kalibri [48]3 years ago
4 0

Responder:

c = 15

Explicação passo a passo:

se -3 é a solução para a expressão x² - 7x - 2c = 0, para obter c, vamos substituir x = -3 na equação (uma vez que é uma raiz)

x² - 7x - 2c = 0

(-3) ² - 7 (-3) - 2c = 0

9 + 21 - 2c = 0

30 - 2c = 0

30 = 2c

Trocar

2c = 30

c = 30/2

c = 15

Portanto, o valor de c é 15

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Step-by-step explanation:

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2 years ago
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Equivalent expression for 7a+21
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Answer:

Step-by-step explanation:

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3 years ago
In a survey of 300 house wires. It was discovered
ruslelena [56]

Answer:

46 housewives read all three magazines.

Step-by-step explanation:

Given:

        n(A) = 150

        n(B) = 200

        n(C) = 156

        n(A∩B) = 48

        n(B∩C) = 60

        n(A∩C) = 52

         n(A∪B∪C) = 300

so we know the relation as:

  n(A∪B∪C) = n(A) + n(B) + n(C) - n(A∩B) - n(B∩C) - n(A∩C) + n(A∩B∩C)

∴ n(A∩B∩C) = n(A) + n(B) + n(C) - n(A∩B) - n(B∩C) - n(A∩C)  - n(A∪B∪C)

                    = 150 + 200+ 156 - 48 - 60 - 52 - 300

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Hence the number of housewives that had read all three magazine is 46.

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Answer:

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