Find f(2)

Find \( f(2) \)

Question:

If

\[ 2f(x)-3f\left(\frac1x\right)=x^2 \qquad (x\ne0) \]

then \( f(2) \) is equal to

(a) \(-\frac74\)
(b) \(\frac52\)
(c) \(-1\)
(d) none of these

Solution:

Replace \(x\) by \(\frac1x\),

\[ 2f\left(\frac1x\right)-3f(x)=\frac1{x^2} \]

Given,

\[ 2f(x)-3f\left(\frac1x\right)=x^2 \]

Solving,

\[ -5f(x)=\frac3{x^2}+2x^2 \]

\[ f(x)=-\frac15\left(\frac3{x^2}+2x^2\right) \]

Put \(x=2\),

\[ f(2) = -\frac15\left(\frac34+8\right) \]

\[ = -\frac{35}{20} = -\frac74 \]

\[ \boxed{\text{Correct Answer: (a)}} \]

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