Question Number 49251 by cesar.marval.larez@gmail.com last updated on 04/Dec/18
Commented by afachri last updated on 05/Dec/18
$$\mathrm{unfortunately}\:\mathrm{i}\:\mathrm{am}\:\mathrm{not}\:\mathrm{learning}\:\mathrm{integral} \\ $$$$\mathrm{yet} \\ $$
Answered by tanmay.chaudhury50@gmail.com last updated on 05/Dec/18
$$\left.\mathrm{1}\right)\int_{\mathrm{0}} ^{\mathrm{1}} \frac{{sin}\left(\frac{\mathrm{5}{x}}{\mathrm{3}}\right)}{{cos}^{\mathrm{2}} \left(\frac{\mathrm{5}{x}}{\mathrm{3}}\right)}{dx} \\ $$$${t}={cos}\left(\frac{\mathrm{5}{x}}{\mathrm{3}}\right)\:\:{so}\:{dt}=−{sin}\left(\frac{\mathrm{5}{x}}{\mathrm{3}}\right)×\frac{\mathrm{5}}{\mathrm{3}}{dx} \\ $$$$\frac{−\mathrm{3}}{\mathrm{5}}{dt}={sin}\left(\frac{\mathrm{5}{x}}{\mathrm{3}}\right){dx} \\ $$$$=\frac{−\mathrm{3}}{\mathrm{5}}\int_{\mathrm{1}} ^{{cos}\left(\frac{\mathrm{5}}{\mathrm{3}}\right)} \:\frac{{dt}}{{t}^{\mathrm{2}} } \\ $$$$=\frac{−\mathrm{3}}{\mathrm{5}}×\mid\frac{−\mathrm{1}}{{t}}\mid_{\mathrm{1}} ^{{cos}\left(\frac{\mathrm{5}}{\mathrm{3}}\right)} \\ $$$$=\frac{\mathrm{3}}{\mathrm{5}}\left\{\frac{\mathrm{1}}{{cos}\left(\frac{\mathrm{5}}{\mathrm{3}}\right)}−\mathrm{1}\right\} \\ $$
Answered by tanmay.chaudhury50@gmail.com last updated on 05/Dec/18
$$\left.\mathrm{2}\right)\int_{\mathrm{0}} ^{\mathrm{1}} {e}^{\frac{\mathrm{3}{x}}{\mathrm{5}}} {cos}\left(\frac{\mathrm{4}{x}}{\mathrm{3}}\right)\:{dx} \\ $$$${let}\:{we}\:{find}\:\:{step}\:\mathrm{1}−{find}\:\int{e}^{{ax}} {cosbx}\:{dx} \\ $$$$ \\ $$$${then}\:{put}\:{a}=\frac{\mathrm{3}}{\mathrm{5}}\:{and}\:{b}=\frac{\mathrm{4}}{\mathrm{3}} \\ $$$${finally}\:{put}\:{upper}\:{and}\:{lower}\:{limit} \\ $$$${method}−\mathrm{1} \\ $$$${I}=\int{e}^{{ax}} {cosbxdx} \\ $$$$={e}^{{ax}} ×\frac{{sinbx}}{{b}}−\int\left[\frac{{d}}{{dx}}\left({e}^{{ax}} \right)\int{cosbxdx}\right]{dx} \\ $$$$=\frac{{e}^{{ax}} {sinbx}}{{b}}−\int{ae}^{{ax}} ×\frac{{sinbx}}{{b}}{dx} \\ $$$$=\frac{{e}^{{ax}} {sinbx}}{{b}}−\frac{{a}}{{b}}\left[{e}^{{ax}} \int{sinbxdx}−\int\left\{\frac{{d}\left({e}^{{ax}} \right)}{{dx}}\int{sinbxdx}\right\}{dx}\right] \\ $$$$={do}−\frac{{a}}{{b}}\left[{e}^{{ax}} ×\frac{−{cosbx}}{{b}}−\int{ae}^{{ax}} ×\frac{−{cosbx}}{{b}}{dx}\right] \\ $$$$={do}−\frac{{a}}{{b}}\left[\frac{−{e}^{{ax}} {cosbx}}{{b}}+\frac{{a}}{{b}}\int{e}^{{ax}} {cosbxdx}\right] \\ $$$$={do}−\frac{{a}}{{b}}\left[\frac{−{e}^{{ax}} {cosbx}}{{b}}+\frac{{a}}{{b}}{I}\right] \\ $$$$=\frac{{e}^{{ax}} {sinbx}}{{b}}+\frac{{a}}{{b}^{\mathrm{2}} }{e}^{{ax}} {cosbx}−\frac{{a}^{\mathrm{2}} }{{b}^{\mathrm{2}} }{I} \\ $$$${I}+\frac{{a}^{\mathrm{2}} }{{b}^{\mathrm{2}} }{I}=\frac{{be}^{{ax}} {sinbx}+{ae}^{{ax}} {cosbx}}{{b}^{\mathrm{2}} } \\ $$$${I}\left(\mathrm{1}+\frac{{a}^{\mathrm{2}} }{{b}^{\mathrm{2}} }\right)=\frac{{e}^{{ax}} \left({bsinbx}+{acosbx}\right)}{{b}^{\mathrm{2}} } \\ $$$${I}\left(\frac{{a}^{\mathrm{2}} +{b}^{\mathrm{2}} }{{b}^{\mathrm{2}} }\right)=\frac{{e}^{{ax}} \left({bsinbx}+{acosbx}\right)}{{b}^{\mathrm{2}} } \\ $$$${I}=\frac{{e}^{{ax}} \left({bsinbx}+{acosbx}\right)}{{a}^{\mathrm{2}} +{b}^{\mathrm{2}} } \\ $$$${now}\:{put}\:{a}=\frac{\mathrm{3}}{\mathrm{5}}\:\:\:{b}=\frac{\mathrm{4}}{\mathrm{3}} \\ $$$${so}\:{required}\:{intregal}\:{is} \\ $$$$\mid\frac{{e}^{\frac{\mathrm{3}}{\mathrm{5}}{x}} \left\{\left(\frac{\mathrm{4}}{\mathrm{3}}{sin}\left(\frac{\mathrm{4}}{\mathrm{3}}{x}\right)+\frac{\mathrm{3}}{\mathrm{5}}{cos}\left(\frac{\mathrm{4}}{\mathrm{3}}{x}\right)\right\}\right.}{\left(\frac{\mathrm{3}}{\mathrm{5}}\right)^{\mathrm{2}} +\left(\frac{\mathrm{4}}{\mathrm{3}}\right)^{\mathrm{2}} }\mid_{\mathrm{0}} ^{\mathrm{1}} \\ $$$$=\left[\frac{{e}^{\frac{\mathrm{3}}{\mathrm{5}}} \left\{\frac{\mathrm{4}}{\mathrm{3}}{sin}\left(\frac{\mathrm{4}}{\mathrm{3}}\right)+\frac{\mathrm{3}}{\mathrm{5}}{cos}\left(\frac{\mathrm{4}}{\mathrm{3}}\right)\right\}}{\left(\frac{\mathrm{3}}{\mathrm{5}}\right)^{\mathrm{2}} +\left(\frac{\mathrm{4}}{\mathrm{3}}\right)^{\mathrm{2}} }\right]−\left[\frac{{e}^{\mathrm{0}} \left\{\frac{\mathrm{4}}{\mathrm{3}}{sin}\mathrm{0}+\frac{\mathrm{3}}{\mathrm{5}}{cos}\left(\mathrm{0}\right)\right.}{\left(\frac{\mathrm{3}}{\mathrm{5}}\right)^{\mathrm{2}} +\left(\frac{\mathrm{4}}{\mathrm{3}}\right)^{\mathrm{2}} }\right] \\ $$$$=\left[\frac{{e}^{\frac{\mathrm{3}}{\mathrm{5}}\left\{\frac{\mathrm{4}}{\mathrm{3}}{sin}\left(\frac{\mathrm{4}}{\mathrm{3}}\right)+\frac{\mathrm{3}}{\mathrm{5}}{cos}\left(\frac{\mathrm{4}}{\mathrm{3}}\right)\right\}−\frac{\mathrm{3}}{\mathrm{5}}} }{\left(\frac{\mathrm{3}}{\mathrm{5}}\right)^{\mathrm{2}} +\left(\frac{\mathrm{4}}{\mathrm{3}}\right)^{\mathrm{2}} }\right]{pls}\:{check}\: \\ $$$$ \\ $$
Commented by tanmay.chaudhury50@gmail.com last updated on 05/Dec/18
Commented by cesar.marval.larez@gmail.com last updated on 05/Dec/18
$${Woooow}\:{my}\:{friend}\:{i}\:{am}\:{without}\:{word} \\ $$$${thank}\:{u}\:{very}\:{much}\:{and}\:{congragulations} \\ $$$${for}\:{this}\:{talent}.\:{i}\:{am}\:{very}\:{grateful}.\: \\ $$$${where}\:{are}\:{u}\:{from}? \\ $$
Commented by tanmay.chaudhury50@gmail.com last updated on 05/Dec/18
$${india}\:\:{nagpur} \\ $$
Commented by cesar.marval.larez@gmail.com last updated on 05/Dec/18
$${U}\:{know}\:{much}\:{u}\:{teach}\:{with}\:{this}\:{work}. \\ $$$${have}\:{u}\:{some}\:{social}\:{conextion}? \\ $$
Commented by tanmay.chaudhury50@gmail.com last updated on 05/Dec/18
$$\:{i}\:{have}\:{facebook}\:{accout}\: \\ $$
Commented by cesar.marval.larez@gmail.com last updated on 06/Dec/18
$${may}\:{i}\:{add}\:{u}? \\ $$
Commented by tanmay.chaudhury50@gmail.com last updated on 06/Dec/18
$${ok}\:{you}\:{can}\:{add}\:{me} \\ $$
Commented by cesar.marval.larez@gmail.com last updated on 07/Dec/18
$${Whats}\:{your}\:{name}? \\ $$
Commented by tanmay.chaudhury50@gmail.com last updated on 07/Dec/18
$${TANMAY}\:\:{CHAUDHURY} \\ $$
Answered by tanmay.chaudhury50@gmail.com last updated on 05/Dec/18
$$\left.\mathrm{2}\right)\int_{\mathrm{0}} ^{\mathrm{1}} {e}^{\frac{\mathrm{3}{x}}{\mathrm{5}}} {cos}\left(\frac{\mathrm{4}}{\mathrm{3}}\right){dx} \\ $$$${altetrnative}\:{method}… \\ $$$$\int{e}^{{ax}} {cosbx}\:{dx}\:\:\:{a}=\frac{\mathrm{3}}{\mathrm{5}}\:\:{b}=\frac{\mathrm{4}}{\mathrm{3}} \\ $$$${p}=\int{e}^{{ax}} {cosbxdx} \\ $$$${q}=\int{e}^{{ax}} {sinbxdx} \\ $$$${p}+{iq}=\int{e}^{{ax}} \left({cosbx}+{isinbx}\right){dx} \\ $$$$=\int{e}^{{ax}} ×{e}^{{ibx}} {dx}=\int{e}^{\left({a}+{ib}\right){x}} {dx} \\ $$$${p}+{iq}=\frac{{e}^{\left({a}+{ib}\right){x}} }{{a}+{ib}} \\ $$$${p}+{iq}=\frac{{e}^{{ax}} ×{e}^{{ibx}} }{\left({a}+{ib}\right)\left({a}−{ib}\right)}×\left({a}−{ib}\right) \\ $$$$=\frac{{e}^{{ax}} }{{a}^{\mathrm{2}} +{b}^{\mathrm{2}} }\left({cosbx}+{isinbx}\right)\left({a}−{ib}\right) \\ $$$${formula}\:{e}^{{i}\alpha} ={cos}\alpha+{isin}\alpha \\ $$$$=\frac{{e}^{{ax}} }{{a}^{\mathrm{2}} +{b}^{\mathrm{2}} }×\left({acosbx}+{iasinbx}−{ibcosbx}+{bsinbx}\right) \\ $$$$=\frac{{e}^{{ax}} }{{a}^{\mathrm{2}} +{b}^{\mathrm{2}} }\left({acosbx}+{bsinbx}\right)+{i}×\frac{{e}^{{ax}} }{{a}^{\mathrm{2}} +{b}^{\mathrm{2}} }\left({asinbx}−{bcosbx}\right) \\ $$$${so}\:{equating}\:{real}\:{and}\:{imaginary}\:{part}\:{both}\:{side} \\ $$$${p}=\int{e}^{{ax}} {cosbxdx}=\frac{{e}^{{ax}} }{{a}^{\mathrm{2}} +{b}^{\mathrm{2}} }\left({acosbx}+{bsinbx}\right) \\ $$$${q}=\int{e}^{{ax}} {sinbxdx}=\frac{{e}^{{ax}} }{{a}^{\mathrm{2}} +{b}^{\mathrm{2}} }\left({asinbx}−{bcosbx}\right) \\ $$$${now}\:\int_{\mathrm{0}} ^{\mathrm{1}} {e}^{\frac{\mathrm{3}{x}}{\mathrm{5}}} {cos}\left(\frac{\mathrm{4}{x}}{\mathrm{3}}\right){dx} \\ $$$$\mid\frac{{e}^{\frac{\mathrm{3}{x}}{\mathrm{5}}} }{\left(\frac{\mathrm{3}}{\mathrm{5}}\right)^{\mathrm{2}} +\left(\frac{\mathrm{4}}{\mathrm{3}}\right)^{\mathrm{2}} }×\left\{\frac{\mathrm{3}}{\mathrm{5}}{cos}\left(\frac{\mathrm{4}{x}}{\mathrm{3}}\right)+\frac{\mathrm{4}}{\mathrm{3}}×{sin}\left(\frac{\mathrm{4}{x}}{\mathrm{3}}\right)\right\}\mid_{\mathrm{0}} ^{\mathrm{1}} \\ $$$${already}\:{solved}.. \\ $$$$ \\ $$
Answered by tanmay.chaudhury50@gmail.com last updated on 05/Dec/18
$$\left.\mathrm{3}\right)\int{sin}^{\mathrm{5}} \left(\mathrm{3}{x}\right){cos}^{\mathrm{2}} \left(\mathrm{3}{x}\right){dx} \\ $$$$\int{sin}\left(\mathrm{3}{x}\right)\left\{\mathrm{1}−{cos}^{\mathrm{2}} \left(\mathrm{3}{x}\right)\right\}^{\mathrm{2}} {cos}^{\mathrm{2}} \left(\mathrm{3}{x}\right){dx} \\ $$$${t}={cos}\left(\mathrm{3}{x}\right) \\ $$$${dt}=−\mathrm{3}{sin}\left(\mathrm{3}{x}\right){dx} \\ $$$$\frac{{dt}}{−\mathrm{3}}={sin}\left(\mathrm{3}{x}\right){dx} \\ $$$$\int\left(\mathrm{1}−{t}^{\mathrm{2}} \right)^{\mathrm{2}} ×{t}^{\mathrm{2}} ×\frac{{dt}}{−\mathrm{3}} \\ $$$$\frac{−\mathrm{1}}{\mathrm{3}}\int\left(\mathrm{1}−\mathrm{2}{t}^{\mathrm{2}} +{t}^{\mathrm{4}} \right){t}^{\mathrm{2}} {dt} \\ $$$$=\frac{−\mathrm{1}}{\mathrm{3}}\int\left({t}^{\mathrm{2}} −\mathrm{2}{t}^{\mathrm{4}} +{t}^{\mathrm{6}} \right){dt} \\ $$$$=\frac{−\mathrm{1}}{\mathrm{3}}\left[\frac{{t}^{\mathrm{3}} }{\mathrm{3}}−\frac{\mathrm{2}{t}^{\mathrm{5}} }{\mathrm{5}}+\frac{{t}^{\mathrm{7}} }{\mathrm{7}}\right]+{c} \\ $$$$=\frac{−\mathrm{1}}{\mathrm{3}}\left[\frac{{cos}^{\mathrm{3}} \left(\mathrm{3}{x}\right)}{\mathrm{3}}−\frac{\mathrm{2}{cos}^{\mathrm{5}} \left(\mathrm{3}{x}\right)}{\mathrm{5}}+\frac{{cos}^{\mathrm{7}} \left(\mathrm{3}{x}\right)}{\mathrm{7}}\right]+{c} \\ $$
Answered by tanmay.chaudhury50@gmail.com last updated on 05/Dec/18
$$\left.\mathrm{4}\right)\int\frac{\mathrm{3}{x}+\mathrm{5}}{\left(\mathrm{1}−{x}\right)\left({x}+\mathrm{3}\right)\left({x}^{\mathrm{2}} −\mathrm{2}\right)}{dx} \\ $$$$\int\frac{\mathrm{3}{x}+\mathrm{5}}{\left(\mathrm{1}−{x}\right)\left({x}+\mathrm{3}\right)\left({x}^{\mathrm{2}} −\mathrm{2}\right)}{dx}=\int\left[\frac{{a}}{\mathrm{1}−{x}}+\frac{{b}}{{x}+\mathrm{3}}+\frac{{c}}{{x}+\sqrt{\mathrm{2}}\:}+\frac{{d}}{{x}−\sqrt{\mathrm{2}}}\right]{dx} \\ $$$$=\int\frac{{a}}{\mathrm{1}−{x}}{dx}+\int\frac{{b}}{{x}+\mathrm{3}}{dx}+\int\frac{{c}}{{x}+\sqrt{\mathrm{2}}}{dx}+\frac{{d}}{{x}−\sqrt{\mathrm{2}}}{dx} \\ $$$$=\left(−{a}\right)\int\frac{{dx}}{{x}−\mathrm{1}}+{b}\int\frac{{dx}}{{x}+\mathrm{3}}+{c}\int\frac{{dx}}{{x}+\sqrt{\mathrm{2}}}+{d}\int\frac{{dx}}{{x}−\sqrt{\mathrm{2}}} \\ $$$$=\left(−{a}\right){ln}\left({x}−\mathrm{1}\right)+{bln}\left({x}+\mathrm{3}\right)+{cln}\left({x}+\sqrt{\mathrm{2}}\:\right)+{dln}\left({x}−\sqrt{\mathrm{2}}\:\right)+{k}\leftarrow\left(\mathrm{1}\right) \\ $$$${now}\:{we}\:{calculate}\:{value}\:{of}\:{a},{b},{c}\:{and}\:{d} \\ $$$$\mathrm{3}{x}+\mathrm{5}={a}\left({x}+\mathrm{3}\right)\left({x}+\sqrt{\mathrm{2}}\:\right)\left({x}−\sqrt{\mathrm{2}}\:\right)+{b}\left(\mathrm{1}−{x}\right)\left({x}+\sqrt{\mathrm{2}}\:\right)\left({x}−\sqrt{\mathrm{2}}\:\right)+{c}\left(\mathrm{1}−{x}\right)\left({x}+\mathrm{3}\right)\left({x}−\sqrt{\mathrm{2}}\:\right)+{d}\left(\mathrm{1}−{x}\right)\left(\left({x}+\mathrm{3}\right)\left({x}+\sqrt{\mathrm{2}}\:\right)\right. \\ $$$${put}\:{x}=\mathrm{1}\:,−\mathrm{3},−\sqrt{\mathrm{2}}\:,\sqrt{\mathrm{2}}\:\:{one}\:{by}\:{one}\:\:{both}\:{side} \\ $$$$ \\ $$$$\mathrm{3}×\mathrm{1}+\mathrm{5}={a}\left(\mathrm{1}+\mathrm{3}\right)\left(\mathrm{1}+\sqrt{\mathrm{2}}\:\right)\left(\mathrm{1}−\sqrt{\mathrm{2}}\:\right) \\ $$$$\mathrm{8}=−\mathrm{4}{a}\:\:\:{a}=−\mathrm{2} \\ $$$$ \\ $$$$\mathrm{3}×−\mathrm{3}+\mathrm{5}={b}\left(\mathrm{1}+\mathrm{4}\right)\left(−\mathrm{3}+\sqrt{\mathrm{2}}\:\right)\left(−\mathrm{3}−\sqrt{\mathrm{2}}\:\right) \\ $$$$−\mathrm{4}={b}×\mathrm{5}×\left(\mathrm{9}−\mathrm{2}\right) \\ $$$${b}=\frac{−\mathrm{4}}{\mathrm{35}} \\ $$$$ \\ $$$$\mathrm{3}×−\sqrt{\mathrm{2}}\:+\mathrm{5}={c}\left(\mathrm{1}+\sqrt{\mathrm{2}}\:\right)\left(−\sqrt{\mathrm{2}}\:+\mathrm{3}\right)\left(−\sqrt{\mathrm{2}}\:−\sqrt{\mathrm{2}}\:\right) \\ $$$$−\mathrm{3}\sqrt{\mathrm{2}}\:+\mathrm{5}={c}\left(\mathrm{1}+\sqrt{\mathrm{2}}\:\right)\left(\mathrm{3}−\sqrt{\mathrm{2}}\:\right)\left(−\mathrm{2}\sqrt{\mathrm{2}}\:\right) \\ $$$${c}=\frac{\mathrm{5}−\mathrm{3}\sqrt{\mathrm{2}}}{\left(\mathrm{1}+\sqrt{\mathrm{2}}\:\right)\left(\sqrt{\mathrm{2}}−\mathrm{3}\right)\left(\mathrm{2}\sqrt{\mathrm{2}}\right)} \\ $$$$ \\ $$$$\mathrm{3}×\sqrt{\mathrm{2}}\:+\mathrm{5}={d}\left(\mathrm{1}−\sqrt{\mathrm{2}}\:\right)\left(\sqrt{\mathrm{2}}\:+\mathrm{3}\right)\left(\sqrt{\mathrm{2}}\:+\sqrt{\mathrm{2}}\:\right) \\ $$$${d}=\frac{\mathrm{3}\sqrt{\mathrm{2}}\:+\mathrm{5}}{\left(\mathrm{1}−\sqrt{\mathrm{2}}\:\right)\left(\mathrm{3}+\sqrt{\mathrm{2}}\:\right)\left(\mathrm{2}\sqrt{\mathrm{2}}\:\right)} \\ $$$${now}\:{put}\:{the}\:{value}\:{in}\:{a}\:,{b},{c}\:{and}\:{d}\:{in}\:{answer}\:\left(\mathrm{1}\right) \\ $$$$ \\ $$$$ \\ $$