Question Number 41288 by mondodotto@gmail.com last updated on 04/Aug/18
$$\boldsymbol{\mathrm{by}}\:\boldsymbol{\mathrm{using}}\:\boldsymbol{\mathrm{the}}\:\boldsymbol{\mathrm{knowledge}}\:\boldsymbol{\mathrm{of}}\: \\ $$$$\boldsymbol{\mathrm{sequence}}\:\boldsymbol{\mathrm{and}}\:\boldsymbol{\mathrm{series}}\:\boldsymbol{\mathrm{show}}\:\boldsymbol{\mathrm{that}} \\ $$$$\boldsymbol{\mathrm{the}}\:\boldsymbol{\mathrm{compound}}\:\boldsymbol{\mathrm{interest}}\:\boldsymbol{\mathrm{is}}\:\boldsymbol{\mathrm{given}}\:\boldsymbol{\mathrm{by}} \\ $$$$\boldsymbol{\mathrm{An}}=\boldsymbol{\mathrm{P}}\left(\mathrm{1}+\frac{\boldsymbol{\mathrm{RT}}}{\mathrm{100}}\right)^{\boldsymbol{\mathrm{n}}} \\ $$
Answered by tanmay.chaudhury50@gmail.com last updated on 05/Aug/18
$${begining}\:{of}\:{the}\:\:\:\:\:\:\:\:\:\:\:{end}\:{of}\:{year}\:\:\:\:\:{end}\:{of}\:{year} \\ $$$$\:\:{year}\left({principle}\right)\:\:\:\:\:\:\:\:−\:\:\:\:{interest}\:\:\:\:\:\:\:\:\:\:\:\:−\:\:{amount} \\ $$$$\left.\mathrm{1}\right)\:\:\:\:\:\:\:{P}\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\_\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\frac{{P}×{R}×\mathrm{1}}{\mathrm{100}}\:\:\:\:\:\:\:\:\:\:−\:\:\:\:\:\:\:\:\:\:{P}+\frac{{P}×{R}×\mathrm{1}}{\mathrm{100}} \\ $$$$\left.\mathrm{2}\right)\:\:\:\:\:\:{P}\left(\mathrm{1}+\frac{{R}}{\mathrm{100}}\right)\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:−\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:{P}\left(\mathrm{1}+\frac{{R}}{\mathrm{100}}\right)×\frac{{R}×\mathrm{1}}{\mathrm{100}}\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:−\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:{P}\left(\mathrm{1}+\frac{{R}}{\mathrm{100}}\right).\frac{{R}}{\mathrm{100}}+{P}\left(\mathrm{1}+\frac{{R}}{\mathrm{100}}\right) \\ $$$$\left.\mathrm{3}\right){P}\left(\mathrm{1}+\frac{{R}}{\mathrm{100}}\right)^{\mathrm{2}} \:\:\:\:\:\:\:\:\:\:\:\:−\:\:\:\:\:{P}\left(\mathrm{1}+\frac{{R}}{\mathrm{100}}\right)^{\mathrm{2}} ×\frac{{R}}{\mathrm{100}}\:\:\:\:−{P}\left\{\mathrm{1}+\frac{{R}}{\mathrm{100}}\right\}^{\mathrm{2}} ×\frac{{R}}{\mathrm{100}}+{P}\left\{\mathrm{1}+\frac{{R}}{\mathrm{100}}\right\}^{\mathrm{2}} \\ $$$${thus} \\ $$$${thus}\:{for}\:{first}\:{year}\:{principle}\left({p}\right)={p}\:\:\:\:{amount}\left({A}\right)={P}\left(\mathrm{1}+\frac{{R}}{\mathrm{100}}\right) \\ $$$${for}\:\mathrm{2}{nd}\:{year}\:\left({p}\right)={p}\left(\mathrm{1}+\frac{{R}}{\mathrm{100}}\right)\:\:\:\:\:\:{amount}\left({A}\right)={p}\left(\mathrm{1}+\frac{{R}}{\mathrm{100}}\right)^{\mathrm{2}} \\ $$$${for}\:\mathrm{3}{rd}\:{year}\left({p}\right)={p}\left(\mathrm{1}+\frac{{R}}{\mathrm{100}}\right)^{\mathrm{2}} \:\:\:{amount}\left({A}\right)={p}\left(\mathrm{1}+\frac{{R}}{\mathrm{100}}\right)^{\mathrm{3}} \\ $$$$ \\ $$$${thus}\:{for}\:\:{n}\:\:{year}\:{amount}\left({A}\right)={p}\left(\mathrm{1}+\frac{{R}}{\mathrm{100}}\right)^{{n}} \\ $$