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Let \(S\) be the set of positive integral values of \(a\) for which \(\frac{a x^2+2(a+1) x+9 a+4}{x^2-8 x+32}<0, \for…

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Let \(S\) be the set of positive integral values of \(a\) for which \(\frac{a x^2+2(a+1) x+9 a+4}{x^2-8 x+32}<0, \forall x \in R\). Then, the number of elements in \(S\) is :

[JEE Main 2024, 31 Jan (Shift 1)]

a

0

b

\(\infty\)

c

1

d

3

✓ Correct answer: a)

0

Explanation

Given \(\frac{a x^2+2(a+1) x+9 a+4}{x^2-8 x+32}<0 \quad \forall x \in \mathbb{R}\)
In \(x^2-8 x+32\), we have \(D=64-128<0\)

\( \therefore x^2-8 x+32>0\) \(\forall x \in \mathbb{R} \)
\( \Rightarrow a x^2+2(a+1) x+9 a+4<0\) \(\forall x \in R \)
\( \Rightarrow a<0\) and \(D<0\)

Since Question has asked for positive integral values of \(a\)

\( \therefore|S|=0\)

but we need positive integral value of a.
So, No solution

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