Question and Answers Forum

# Advanced Calculus # Φ = ∫_0 ^( 1) (((ln^ ( (1/(1− x)) ))/x) )^( 3) dx =^? 3 ( ζ (2 ) + ζ (3 )) −−−− solution−−−− Φ =^(I.B.P) [ (( 1)/(2x^( 2) )) ln^( 3) ( 1−x)]_0 ^1 +(3/2) ∫_0 ^( 1) (( ln^( 2) (1− x ))/(x^( 2) (1 − x ))) dx = (1/2) lim_( ξ →1^(− ) ) ((ln^( 3) ( 1− ξ ))/ξ^( 2) ) +(3/2)[∫_0 ^( 1) (( ln^( 2) ( 1− x ))/x)dx = 2 ζ (3)] + (3/2)[∫_0 ^( 1) (( ln^( 2) ( 1−x))/x^( 2) ) dx = (π^( 2) /3) = 2ζ (2 )] +(3/2)∫_0 ^( 1) (( ln^( 2) (1− x))/(1−x)) dx} =(1/2) lim_( ξ →1^( −) ) {((ln^( 3) ( 1−ξ ))/ξ^( 2) ) −ln^( 3) (1− ξ ) } +(3/2) (2ζ (3 )) +(3/2) ( 2ζ (2 )) = 3( ζ (3 ) + 3ζ (2 ) ) ■ m.n

$$ \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:#\:\mathrm{Advanced}\:\:\:\mathrm{Calculus}\:# \\ $$$$\:\:\:\:\:\:\:\:\Phi\:=\:\int_{\mathrm{0}} ^{\:\mathrm{1}} \left(\frac{{ln}^{\:} \:\left(\:\frac{\mathrm{1}}{\mathrm{1}−\:{x}}\:\:\right)}{{x}}\:\right)^{\:\mathrm{3}} {dx}\:\overset{?} {=}\:\mathrm{3}\:\left(\:\zeta\:\left(\mathrm{2}\:\right)\:+\:\zeta\:\left(\mathrm{3}\:\right)\right) \\ $$$$\:\:\:\:\:\:−−−−\:\:{solution}−−−− \\ $$$$\:\:\:\:\:\:\:\:\Phi\:\overset{\mathrm{I}.\mathrm{B}.\mathrm{P}} {=}\:\left[\:\frac{\:\mathrm{1}}{\mathrm{2}{x}^{\:\mathrm{2}} }\:{ln}^{\:\mathrm{3}} \left(\:\mathrm{1}−{x}\right)\right]_{\mathrm{0}} ^{\mathrm{1}} +\frac{\mathrm{3}}{\mathrm{2}}\:\int_{\mathrm{0}} ^{\:\mathrm{1}} \frac{\:{ln}^{\:\mathrm{2}} \:\left(\mathrm{1}−\:{x}\:\right)}{{x}^{\:\mathrm{2}} \:\left(\mathrm{1}\:−\:{x}\:\right)}\:{dx} \\ $$$$\:\:\:\:\:\:\:\:=\:\frac{\mathrm{1}}{\mathrm{2}}\:{lim}_{\:\xi\:\rightarrow\mathrm{1}^{−\:} } \:\frac{{ln}^{\:\mathrm{3}} \left(\:\mathrm{1}−\:\xi\:\right)}{\xi^{\:\mathrm{2}} }\: \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:+\frac{\mathrm{3}}{\mathrm{2}}\left[\int_{\mathrm{0}} ^{\:\mathrm{1}} \frac{\:{ln}^{\:\mathrm{2}} \left(\:\mathrm{1}−\:{x}\:\right)}{{x}}{dx}\:=\:\mathrm{2}\:\zeta\:\left(\mathrm{3}\right)\right] \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:+\:\frac{\mathrm{3}}{\mathrm{2}}\left[\int_{\mathrm{0}} ^{\:\mathrm{1}} \frac{\:{ln}^{\:\mathrm{2}} \left(\:\mathrm{1}−{x}\right)}{{x}^{\:\mathrm{2}} }\:{dx}\:=\:\frac{\pi^{\:\mathrm{2}} }{\mathrm{3}}\:=\:\mathrm{2}\zeta\:\left(\mathrm{2}\:\right)\right]\: \\ $$$$\left.\:\:\:\:\:\:\:\:\:\:\:\:+\frac{\mathrm{3}}{\mathrm{2}}\int_{\mathrm{0}} ^{\:\mathrm{1}} \frac{\:{ln}^{\:\mathrm{2}} \left(\mathrm{1}−\:{x}\right)}{\mathrm{1}−{x}}\:{dx}\right\} \\ $$$$\:\:\:\:\:\:\:\:\:\:=\frac{\mathrm{1}}{\mathrm{2}}\:{lim}_{\:\xi\:\rightarrow\mathrm{1}^{\:−} } \left\{\frac{{ln}^{\:\mathrm{3}} \left(\:\mathrm{1}−\xi\:\right)}{\xi^{\:\mathrm{2}} }\:\:−{ln}^{\:\mathrm{3}} \left(\mathrm{1}−\:\xi\:\right)\:\right\} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:+\frac{\mathrm{3}}{\mathrm{2}}\:\left(\mathrm{2}\zeta\:\left(\mathrm{3}\:\right)\right)\:\:+\frac{\mathrm{3}}{\mathrm{2}}\:\left(\:\mathrm{2}\zeta\:\left(\mathrm{2}\:\right)\right) \\ $$$$\:\:\:\:\:\:\:\:\:\:=\:\:\mathrm{3}\left(\:\:\:\zeta\:\left(\mathrm{3}\:\right)\:+\:\mathrm{3}\zeta\:\left(\mathrm{2}\:\right)\:\:\right)\:\:\:\:\:\:\:\blacksquare\:\:\:{m}.{n}\:\:\: \\ $$$$ \\ $$

Question Number 160733 Answers: 0 Comments: 0

Question Number 160807 Answers: 0 Comments: 0

−1≤a_0 ≤b_0 ≤c_0 ≤1 ∀n∈N a_(n+1) =∫_(−1) ^1 min(x,b_n ,c_n )dx b_(n+1) =∫_(−1) ^1 mil(x,a_n ,c_n )dx c_(n+1) =∫_(−1) ^1 max(x,b_n ,a_n )dx mil(a,b,c) est le terme median de (a,b,c) nature de (a_n ),(b_n ),(c_n )

$$−\mathrm{1}\leqslant{a}_{\mathrm{0}} \leqslant{b}_{\mathrm{0}} \leqslant{c}_{\mathrm{0}} \leqslant\mathrm{1} \\ $$$$\forall{n}\in\mathbb{N}\: \\ $$$${a}_{{n}+\mathrm{1}} =\int_{−\mathrm{1}} ^{\mathrm{1}} {min}\left({x},{b}_{{n}} ,{c}_{{n}} \right){dx} \\ $$$${b}_{{n}+\mathrm{1}} =\int_{−\mathrm{1}} ^{\mathrm{1}} {mil}\left({x},{a}_{{n}} ,{c}_{{n}} \right){dx} \\ $$$${c}_{{n}+\mathrm{1}} =\int_{−\mathrm{1}} ^{\mathrm{1}} {max}\left({x},{b}_{{n}} ,{a}_{{n}} \right){dx} \\ $$$${mil}\left({a},{b},{c}\right)\:{est}\:{le}\:{terme}\:{median}\:{de}\:\left({a},{b},{c}\right) \\ $$$${nature}\:{de}\:\left({a}_{{n}} \right),\left({b}_{{n}} \right),\left({c}_{{n}} \right) \\ $$$$ \\ $$

Question Number 160645 Answers: 2 Comments: 1

∫ sin^8 x dx =?

$$\:\int\:\mathrm{sin}\:^{\mathrm{8}} \mathrm{x}\:\mathrm{dx}\:=? \\ $$

Question Number 160636 Answers: 1 Comments: 0

prove that ∫_(0 ) ^( 1) (((tanh^( −1) ( x ))/x) )^( 2) = ζ ( 2 ) ■ m.n

$$ \\ $$$$\:\:\:\:\:\:\:\:{prove}\:{that} \\ $$$$ \\ $$$$\:\:\:\:\:\:\:\:\int_{\mathrm{0}\:\:} ^{\:\mathrm{1}} \left(\frac{{tanh}^{\:−\mathrm{1}} \left(\:{x}\:\right)}{{x}}\:\right)^{\:\mathrm{2}} =\:\zeta\:\left(\:\mathrm{2}\:\right)\:\:\:\:\:\:\:\:\blacksquare\:{m}.{n}\:\:\:\: \\ $$$$ \\ $$$$ \\ $$

Question Number 160597 Answers: 1 Comments: 0

∫_0 ^( (π/2)) (dx/(2−cos x)) =?

$$\:\:\:\int_{\mathrm{0}} ^{\:\frac{\pi}{\mathrm{2}}} \:\frac{\mathrm{dx}}{\mathrm{2}−\mathrm{cos}\:\mathrm{x}}\:=? \\ $$

Question Number 160594 Answers: 1 Comments: 0

∫ (dx/(1−tan^2 (x))) =?