MathematicsMedium64×since 2002Q2963If b is very small as compared to the value of a, so that the cube and other higher powers of ba{b \over a}ab can be neglected in the identity 1a−b+1a−2b+1a−3b+.....+1a−nb=αn+βn2+γn3{1 \over {a - b}} + {1 \over {a - 2b}} + {1 \over {a - 3b}} + ..... + {1 \over {a - nb}} = \alpha n + \beta {n^2} + \gamma {n^3}a−b1+a−2b1+a−3b1+.....+a−nb1=αn+βn2+γn3, then the value of γ\gammaγ is :Aa2+b3a3{{{a^2} + b} \over {3{a^3}}}3a3a2+bBa+b3a2{{a + b} \over {3{a^2}}}3a2a+bCb23a3{{{b^2}} \over {3{a^3}}}3a3b2Da+b23a3{{a + {b^2}} \over {3{a^3}}}3a3a+b2Check answerSkip