Question Number 56140 by gunawan last updated on 11/Mar/19
$$\mathrm{The}\:\mathrm{value}\:\mathrm{of}\:\:\: \\ $$$$\mathrm{2}\:{C}_{\mathrm{0}} +\frac{\mathrm{2}^{\mathrm{2}} }{\mathrm{2}}{C}_{\mathrm{1}} +\frac{\mathrm{2}^{\mathrm{3}} }{\mathrm{3}}{C}_{\mathrm{2}} +\frac{\mathrm{2}^{\mathrm{4}} }{\mathrm{4}}{C}_{\mathrm{3}} +…+\frac{\mathrm{2}^{\mathrm{11}} }{\mathrm{11}}{C}_{\mathrm{10}} \:\:\mathrm{is} \\ $$
Answered by tanmay.chaudhury50@gmail.com last updated on 11/Mar/19
$$\left(\mathrm{1}+{x}\right)^{\mathrm{10}} ={c}_{\mathrm{0}} {x}^{\mathrm{0}} +{c}_{\mathrm{1}} {x}+{c}_{\mathrm{2}} {x}^{\mathrm{2}} +…+{c}_{\mathrm{10}} {x}^{\mathrm{10}} \\ $$$$\int\left(\mathrm{1}+{x}\right)^{\mathrm{10}} {dx}=\int\left({c}_{\mathrm{0}} {x}^{\mathrm{0}} +{c}_{\mathrm{1}} {x}^{} +{c}_{\mathrm{2}} {x}^{\mathrm{2}} +..+{c}_{\mathrm{10}} {x}^{\mathrm{10}} \right){dx} \\ $$$$\frac{\left(\mathrm{1}+{x}\right)^{\mathrm{11}} }{\mathrm{11}}={c}_{\mathrm{0}} ×\frac{{x}^{\mathrm{1}} }{\mathrm{1}}+{c}_{\mathrm{1}} ×\frac{{x}^{\mathrm{2}} }{\mathrm{2}}+{c}_{\mathrm{2}} ×\frac{{x}^{\mathrm{3}} }{\mathrm{3}}+…+{c}_{\mathrm{10}} ×\frac{{x}^{\mathrm{11}} }{\mathrm{11}}+{C} \\ $$$${put}\:{x}=\mathrm{0}\:{both}\:{side}\:{to}\:{find}\:{constant}\:{value}\:{of}\:{C} \\ $$$$\frac{\mathrm{1}}{\mathrm{11}}={C} \\ $$$${now}\:{put}\:{both}\:{side}\:{x}=\mathrm{2}\: \\ $$$$\frac{\left(\mathrm{1}+\mathrm{2}\right)^{\mathrm{11}} }{\mathrm{11}}={c}_{\mathrm{0}} ×\frac{\mathrm{2}^{\mathrm{1}} }{\mathrm{1}}+{c}_{\mathrm{1}} ×\frac{\mathrm{2}^{\mathrm{2}} }{\mathrm{2}}+{c}_{\mathrm{2}} ×\frac{\mathrm{2}^{\mathrm{3}} }{\mathrm{3}}+…+{c}_{\mathrm{10}} ×\frac{\mathrm{2}^{\mathrm{11}} }{\mathrm{11}}+\frac{\mathrm{1}}{\mathrm{11}} \\ $$$${so}\:{required}\:{answer}\:{is} \\ $$$$\frac{\mathrm{3}^{\mathrm{11}} }{\mathrm{11}}−\frac{\mathrm{1}}{\mathrm{11}}={c}_{\mathrm{0}} ×\frac{\mathrm{2}^{\mathrm{1}} }{\mathrm{1}}+{c}_{\mathrm{1}} ×\frac{\mathrm{2}^{\mathrm{2}} }{\mathrm{2}}+{c}_{\mathrm{2}} ×\frac{\mathrm{2}^{\mathrm{3}} }{\mathrm{3}}+…+{c}_{\mathrm{10}} ×\frac{\mathrm{2}^{\mathrm{11}} }{\mathrm{11}} \\ $$$$\frac{\mathrm{3}^{\mathrm{11}} −\mathrm{1}}{\mathrm{11}}\leftarrow{it}\:{is}\:{the}\:{answer} \\ $$