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vampirchik [111]
3 years ago
12

(CESGRANRIO) Determine o parâmetro m na equação x²+mx+m²-m-12=0, de modo que ela tenha uma raíz nula e outra positiva.

Mathematics
1 answer:
slavikrds [6]3 years ago
4 0
Vamos lá. 

<span>Pede-se para determinar o parâmetro "m" da equação abaixo, sabendo-se que uma raiz é nula e a outra é positiva: </span>

<span>x² + mx + m² - m - 12 = 0 </span>

<span>Veja que se uma raiz é nula (é igual a zero), então vamos substituir o "x" por "0", na equação acima: </span>

<span>0² + m*0 + m² - m - 12 = 0 </span>
<span>0 + 0 + m² - m - 12 = 0 </span>
<span>m² - m - 12 = 0 ------resolvendo essa equação do 2º grau você encontrará as seguintes raízes: </span>

<span>m' = -3 </span>
<span>m'' = 4 </span>

<span>Dessa forma, vamos substituir "m" por (-3) e por 4 e ver se a equação terá uma raiz nula e outra positiva. Vamos ver? </span>

<span>Substituindo "m" por "-3", ficamos com: </span>

<span>x² - 3x + (-3)² - (-3) - 12 = 0 </span>
<span>x² - 3x + 9 + 3 - 12 = 0 </span>
<span>x² - 3x +12 - 12 = 0 </span>
<span>x² - 3x = 0 <------Veja que as raízes dessa equação são: x' = 0 e x'' = 3 </span>
<span>Veja que para m = -3, a equação se verifica, pois temos uma raiz igual a "0" e a outra positiva (igual a 3). </span>

<span>Agora vamos substituir "m" por 4 na equação original: </span>

<span>x² + 4x + 4² - 4 - 12 = 0 </span>
<span>x² + 4x + 16 - 16 = 0 </span>
<span>x² + 4x = 0 <----- Veja que as raízes dessa equação são: x' = 0 e x'' = -4. </span>
<span>Observe que, para m = 4, a equação NÃO se verifica, pois temos uma raiz igual a "0" e a outra negativa (igual a -4). E no enunciado é informado que uma raiz deverá ser nula e a outra positiva. Como deu uma nula e a outra negativa, então m = 4 não convém. </span>

<span>Logo, o valor de "m" deverá ser: </span>

<span>m = -3 <----Pronto. Essa é a resposta. </span>
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Step-by-step explanation:

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The given data can be presented as follows;

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1) 5.25            {}                          273

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3) 7.25            {}                         377

4) 9.25            {}                         481

From the given data, we have the ratio Towers/Customer (thousands) given as follows;

For 1), we have;

273 Towers/(5.25 thousands customers) = 52 Towers/(Thousand customer)

For 2), we have;

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