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How to solve such questions?

Is there easy method?

Because trial and error doesn't work.

1 Answer

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1 votes
We can enumerate the sequence to find the coefficients,

i.e. {3+2(0),3+2(1),3+2(2),...} = {3,5,7,9,11...}

Now we can form the equation as:

f(x) = $3x^{0}+5x^{1}+7x^{2}+9x^{3}+...$  --> 1

Now we can take $xf\left ( x \right )$

ie. $xf\left ( x \right ) = 3x^{1}+5x^{2}+7x^{3}+...$  ---> 2

Now subtracting first equation from second we get,

$(1-x)f\left ( x \right ) = 3x^{0}+2x^{1}+2x^{2}+2x^{3}...$

Solve for f(x) we get option D.

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