If α and β are the roots of the polynomial f(x) = x2 + x + 1 then the value of \(\rm \frac{1}{\alpha}+\frac{1}{\beta}\) will be :

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Bihar STET TGT (Maths) Official Paper-I (Held On: 04 Sept, 2023 Shift 2)
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  1. 0
  2. 1
  3. -1
  4. None of these 

Answer (Detailed Solution Below)

Option 3 : -1
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Detailed Solution

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Concept -

If α and β are the roots of the polynomial f(x) = ax2 + bx + c then

sum of roots = -b/a

product of roots = c/a

Explanation -

Now we have -

If α and β are the roots of the polynomial f(x) = x2 + x + 1

then α + β = -1 .....(i)

and α.β = 1...... (ii)

Now we want to find the value of  \(\rm \frac{1}{\alpha}+\frac{1}{\beta}\)

\(\frac{\alpha+\beta}{\alpha.\beta}\)

Now put the value of equation (i) and (ii) we get -

= -1/1 = -1

Hence option (3) is true.

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