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Category: Integration

Hard-integral-determinant-a-b-c-f-g-h-j-k-l-dl-dk-dj-dh-dg-df-dc-db-da-

Question Number 202418 by MathematicalUser2357 last updated on 26/Dec/23 $$\mathrm{Hard}\:\mathrm{integral} \\ $$$$\int\int\int\int\int\int\int\int\int\begin{vmatrix}{{a}}&{{b}}&{{c}}\\{{f}}&{{g}}&{{h}}\\{{j}}&{{k}}&{{l}}\end{vmatrix}{dl}\:{dk}\:{dj}\:{dh}\:{dg}\:{df}\:{dc}\:{db}\:{da}= \\ $$ Answered by Frix last updated on 26/Dec/23 $$\mathrm{Not}\:\mathrm{hard}\:\mathrm{at}\:\mathrm{all} \\ $$$$=\frac{{abcfghjkl}}{\mathrm{8}}\left({a}\left({gl}−{hk}\right)−{b}\left({fl}−{hj}\right)+{c}\left({fk}−{gj}\right)\right) \\…

The-value-of-g-x-f-g-x-dx-is-

Question Number 202415 by MathematicalUser2357 last updated on 26/Dec/23 $$\mathrm{The}\:\mathrm{value}\:\mathrm{of}\:\int{g}'\left({x}\right){f}'\left({g}\left({x}\right)\right){dx}\:\mathrm{is}… \\ $$ Answered by cortano12 last updated on 26/Dec/23 $$\:\mathrm{let}\:\mathrm{u}=\mathrm{g}\left(\mathrm{x}\right)\Rightarrow\mathrm{du}=\:\mathrm{g}'\left(\mathrm{x}\right)\:\mathrm{dx} \\ $$$$\:\mathrm{I}=\:\int\:\mathrm{g}'\left(\mathrm{x}\right)\:\mathrm{f}\:'\left(\mathrm{g}\left(\mathrm{x}\right)\right)\:\mathrm{dx}\: \\ $$$$\:\:\:=\:\int\:\mathrm{f}\:'\left(\mathrm{u}\right)\:\mathrm{du}=\:\int\:\frac{\mathrm{df}\left(\mathrm{u}\right)}{\mathrm{du}}.\:\mathrm{du} \\…

Question-202406

Question Number 202406 by mou0113 last updated on 26/Dec/23 Answered by witcher3 last updated on 26/Dec/23 $$\mathrm{f}\left(\mathrm{s}\right)=\int_{\mathrm{0}} ^{\infty} \frac{\mathrm{t}^{\mathrm{s}} }{\left(\mathrm{1}+\mathrm{t}^{\mathrm{2}} \right)^{\mathrm{2}} }\mathrm{dt}\Rightarrow\mathrm{f}'\left(\mathrm{0}\right)=\int_{\mathrm{0}} ^{\infty} \frac{\mathrm{ln}\left(\mathrm{x}\right)}{\left(\mathrm{1}+\mathrm{x}^{\mathrm{2}} \right)^{\mathrm{2}}…

P-rove-that-dx-b-4-2ax-2-c-tan-1-2-a-x-c-b-4-2-a-c-b-4-C-if-a-c-b-4-gt-0-

Question Number 202388 by Calculusboy last updated on 25/Dec/23 $$\:\:\boldsymbol{{P}}\:\boldsymbol{{rove}}\:\boldsymbol{{that}}:\:\:\:\:\int\:\frac{\boldsymbol{{dx}}}{\boldsymbol{{b}}^{\mathrm{4}} +\mathrm{2}\boldsymbol{{ax}}^{\mathrm{2}} +\boldsymbol{{c}}}=\frac{\boldsymbol{{tan}}^{−\mathrm{1}} \left(\frac{\sqrt{\mathrm{2}}\sqrt{\boldsymbol{{a}}}\boldsymbol{{x}}}{\:\sqrt{\boldsymbol{{c}}+\boldsymbol{{b}}^{\mathrm{4}} }}\right)}{\:\sqrt{\mathrm{2}}\sqrt{\boldsymbol{{a}}}\sqrt{\boldsymbol{{c}}+\boldsymbol{{b}}^{\mathrm{4}} }}+\boldsymbol{{C}} \\ $$$$\boldsymbol{{if}}\:\:\boldsymbol{{a}}\centerdot\left(\boldsymbol{{c}}+\boldsymbol{{b}}^{\mathrm{4}} \right)>\mathrm{0} \\ $$$$ \\ $$ Answered by witcher3…

sin-3x-1-sin-3-x-dx-

Question Number 202125 by Calculusboy last updated on 21/Dec/23 $$\int\:\frac{\boldsymbol{{sin}}\left(\mathrm{3}\boldsymbol{{x}}\right)}{\mathrm{1}+\boldsymbol{{sin}}^{\mathrm{3}} \boldsymbol{{x}}}\boldsymbol{{dx}} \\ $$ Answered by Frix last updated on 21/Dec/23 $$\mathrm{Let}\:{s}=\mathrm{sin}\:{x} \\ $$$$\frac{\mathrm{sin}\:\mathrm{3}{x}}{\mathrm{1}+\mathrm{sin}^{\mathrm{3}} \:{x}}=\frac{{s}\left(\mathrm{4}{s}^{\mathrm{2}} −\mathrm{3}\right)}{\left({s}+\mathrm{1}\right)\left({s}^{\mathrm{2}}…

Question-202127

Question Number 202127 by Calculusboy last updated on 21/Dec/23 Answered by qaz last updated on 21/Dec/23 $$\int_{\pi/\mathrm{6}} ^{\pi/\mathrm{3}} \frac{{dx}}{\mathrm{1}+\mathrm{tan}^{\pi} \:{x}}=\int_{\pi/\mathrm{6}} ^{\pi/\mathrm{3}} \frac{{dx}}{\mathrm{1}+\mathrm{cot}\:^{\pi} {x}}=\frac{\mathrm{1}}{\mathrm{2}}\int_{\pi/\mathrm{6}} ^{\pi/\mathrm{3}} \left(\frac{\mathrm{1}}{\mathrm{1}+\mathrm{tan}^{\pi}…