∫ 0 1 x 2 2 x ln x d x
If the above integral can be expressed in the highly unusual form
ln j ( k ) − a li ( b ) + c + d γ + ln ( h ln f ( g ) )
where a , b , c , d , f , g , h , j , k are positive integers and the above expression is in simplest form, find a + b + c + d + f + g + h + j + k .
Notations :
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After determined integration by parts, we have ∫ x 2 e a x ln x d x = ( a 1 x 2 − a 2 2 x ) e a x ln x + a 2 2 ( e a x − 1 ) ln x − ( a 2 1 − a 3 3 ) e a x − a 3 2 ∫ x e a x − 1 d x and hence ∫ 0 1 x 2 e a x ln x d x = = = = − ( a 2 1 − a 3 3 ) e a − a 3 3 − a 3 2 ∫ 0 1 x e a x − 1 d x − ( a 2 1 − a 3 3 ) e a − a 3 3 − a 3 2 ∫ 0 a x e x − 1 d x − ( a 2 1 − a 3 3 ) e a − a 3 3 − a 3 2 [ l i ( e a ) − ln a − γ ] a 3 − 2 l i ( e a ) + 3 ( e a − 1 ) + 2 γ + ln a 2 − a e a for any a > 0 . Putting a = ln 2 , we obtain ∫ 0 1 x 2 2 x ln x d x = ( ln 2 ) 3 − 2 l i ( 2 ) + 3 + 2 γ + ln ( 4 1 ( ln 2 ) 2 ) making the answer 2 + 2 + 3 + 2 + 2 + 2 + 4 + 3 + 2 = 2 2 .
Alternatively, with less integration by parts, we could evaluate ∫ 0 1 e a x ln x d x = a γ + ln a − l i ( e a ) and differentiate this twice with respect to a .