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0 votes
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in Polynomials by (37.4k points)
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If α and β are the two zeroes of a polynomial x2 – 5x + 6 then the value of 1/a2 + 1/β2 is ...............

A) 13/36

B) 17/36

C) 19/36

D) 23/36

2 Answers

+2 votes
by (57.0k points)
selected by
 
Best answer

Correct option is (A) 13/36

\(\because\) \(\alpha+\beta\) \(=\frac{-(-5)}1\) = 5 and \(\alpha\beta\) \(=\frac61\) = 6

\(\therefore\) \(\frac{\alpha+\beta}{\alpha\beta}=\frac56\)

\(\Rightarrow\) \(\frac{1}{\alpha}+\frac{1}{\beta}\) \(=\frac56\)

\(\therefore\) \((\frac{1}{\alpha}+\frac{1}{\beta})^2\) \(=(\frac56)^2\)

\(\Rightarrow\) \(\frac{1}{\alpha^2}+\frac{1}{\beta^2}+\frac2{\alpha\beta}\) \(=\frac{25}{36}\)

\(\Rightarrow\) \(\frac{1}{\alpha^2}+\frac{1}{\beta^2}\) \(=\frac{25}{36}-\frac2{\alpha\beta}\)

\(=\frac{25}{36}-\frac26\) \(=\frac{25-12}{36}=\frac{13}{36}\)

+1 vote
by (41.0k points)

Correct option is A) 13/36

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