Evaluate the following integral ∫_1^2dx/x(1+x^4 )
∫_1^2dx/x(1+x^4 ) let x^4=u →4x^3 dx=du→x^3 dx=du/4x=1 →u=1,x=2→u=16∴I=∫_1^2dx/x(1+x^4 ) =∫_1^2(x^3 dx)/(x^4 (1+x^4 ) )=1/4 ∫_1^16du/u(1+u) = 1/4 ∫_1^16[1/u-1/(u+1)] du=1/4 [lnu-ln(1+u) ]_1^16=1/4 [ln16-ln17-(ln1-ln2 )] =1/4 [ln16-ln17+ln2 ]=1/4 ln(32/17)
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∫_1^2dx/x(1+x^4 ) let x^4=u →4x^3 dx=du→x^3 dx=du/4
need an explanation for this answer? contact us directly to get an explanation for this answerx=1 →u=1,x=2→u=16
∴I=∫_1^2dx/x(1+x^4 ) =∫_1^2(x^3 dx)/(x^4 (1+x^4 ) )=1/4 ∫_1^16du/u(1+u)
= 1/4 ∫_1^16[1/u-1/(u+1)] du=1/4 [lnu-ln(1+u) ]_1^16
=1/4 [ln16-ln17-(ln1-ln2 )] =1/4 [ln16-ln17+ln2 ]=1/4 ln(32/17)