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0-1-x-tanh-1-x-1-x-2-dx-1-24-pi-2-6-




Question Number 176542 by mnjuly1970 last updated on 20/Sep/22
    Ω = ∫_0 ^( 1) (( x.tanh^( −1) (x))/((1+x)^( 2) ))dx= (1/(24)) (π^( 2) −6)
Ω=01x.tanh1(x)(1+x)2dx=124(π26)
Answered by Peace last updated on 20/Sep/22
∫_0 ^1 (x/((1+x)^2 ))tg^− (x)dx  tanh^− (x)=(1/2)(ln(1+x)−ln(1−x))  (x/((1+x)^2 ))=(1/(1+x))−(1/((1+x)^2 ))  2Ω=∫_0 ^1 ((ln(1+x))/(1+x))−((ln(1+x))/((1+x)^2 ))dx+∫_0 ^1 ((ln(1−x))/((1+x)^2 ))dx−∫_0 ^1 ((ln(1−x))/(1+x))dx  =(1/2)[ln^2 (1+x)]_0 ^1 +[((ln(1+x))/(1+x))]_0 ^1 −∫_0 ^1 (1/((1+x)^2 ))+A+B  =((ln^2 (2))/2)+((ln(2))/2)+(1/2)+A+B  A=lim_(x→1) ∫_0 ^x ((ln(1−t))/((1+t)^2 ))dt=lim_(x→1) {−((ln(1−x))/(1+x))−∫_0 ^x (1/(1−t^2 )).dt}  =lim_(x→1) −((ln(1−x))/(1+x))−(1/2)∫_0 ^x (1/(1−t))+(1/(1+t))dt  =lim_(x→1) −((ln(1−x))/(1+x))+((ln(1−x))/2)−((ln(1+x))/2)  =−((ln(2))/2)  −B=∫_0 ^1 ((ln(1−x))/(1+x))dx  x=((1−t)/(1+t)),=−1+(2/(1+t))⇒dt=−((2dt)/((1+t)^2 ))  2∫_0 ^1 ((ln(((2t)/(1+t))))/(2/((1+t)))).(1/((1+t)^2 ))dt=∫_0 ^1 ((ln(2t)−ln(1+t))/(1+t))dt  =∫_0 ^1 ((ln(2))/(1+t))+((ln(t))/(1+t))−((ln(1+t))/(1+t))dt  =ln^2 (2)−((ln^2 (2))/2)+∫_0 ^1 ((ln(t))/(1+t))dt=((ln^2 (2))/2)+∫_0 ^1 ((ln(1−(−t))/(−t))d(−t)  =((ln^2 (2))/2)−Li_2 (−1)  B=−((ln^2 (2))/2)+Li_2 (−1)  2Ω=((ln^2 (2))/2)+((ln(2))/2)+(1/2)+A+B  =((ln^2 (2))/2)+((ln(2))/2)+(1/2)−((ln(2))/2)−((ln^2 (2))/2)+Li_2 (−1)  =(1/2)+Li_2 (−1)=(1/2)+(π^2 /(12))=(1/(12))(π^2 −6)  Ω=(1/(24))(π^2 −6)
01x(1+x)2tg(x)dxtanh(x)=12(ln(1+x)ln(1x))x(1+x)2=11+x1(1+x)22Ω=01ln(1+x)1+xln(1+x)(1+x)2dx+01ln(1x)(1+x)2dx01ln(1x)1+xdx=12[ln2(1+x)]01+[ln(1+x)1+x]01011(1+x)2+A+B=ln2(2)2+ln(2)2+12+A+BA=limx10xln(1t)(1+t)2dt=limx1{ln(1x)1+x0x11t2.dt}=limx1ln(1x)1+x120x11t+11+tdt=limx1ln(1x)1+x+ln(1x)2ln(1+x)2=ln(2)2B=01ln(1x)1+xdxx=1t1+t,=1+21+tdt=2dt(1+t)2201ln(2t1+t)2(1+t).1(1+t)2dt=01ln(2t)ln(1+t)1+tdt=01ln(2)1+t+ln(t)1+tln(1+t)1+tdt=ln2(2)ln2(2)2+01ln(t)1+tdt=ln2(2)2+01ln(1(t)td(t)=ln2(2)2Li2(1)B=ln2(2)2+Li2(1)2Ω=ln2(2)2+ln(2)2+12+A+B=ln2(2)2+ln(2)2+12ln(2)2ln2(2)2+Li2(1)=12+Li2(1)=12+π212=112(π26)Ω=124(π26)
Commented by Tawa11 last updated on 22/Sep/22
Great sir
Greatsir
Commented by Peace last updated on 23/Sep/22
thank You nice Day
thankYouniceDay

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