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Question Number 200691 by sonukgindia last updated on 22/Nov/23

Commented by aleks041103 last updated on 22/Nov/23

a,b∈Z?  or just a,b∈R

a,bZ?orjusta,bR

Answered by witcher3 last updated on 22/Nov/23

if b≥0=x^(2b) −x^b +1∼1  f(x)=(x^a /(x^(2b) −x^b +1))∼x^a  integrable if  a+1>0  a>−1=in ∞ x^(2b) −x^b +1∼x^(2b)   f(x)∼x^(a−2b)  integrabl if  2b−a>1  2b>a+1 since b>0 ∣2b∣>∣a+1∣  b<0   x^(2b) −x^b +1∼x^(2b)  in zero  f(x)∼x^(a−2b)  integrabl ⇔ a−2b>1  in ∞ f(x)=∼x^a [integrabl if a<−1  2b<a+1<0  ⇒∣2b∣>∣a+1∣  ⇔∀(a,b)∈R ∣2b∣>∣a+1∣  f(x)=∫_0 ^∞ (x^a /(x^(2b) −x^b +1))dx=∫_0 ^∞ ((x^a (x^b +1))/(x^(3b) +1))dx  x^(3b) =t=∫_0 ^∞ ((t^((a+b)/(3b)) +t^(a/(3b)) )/(1+t)).(t^((1/(3b))−1) /(1+t))dt  =∫_0 ^∞ ((t^(((a+b+1)/(3b))−1) +t^(((a+1)/(3b))−1) )/(1+t))=β(((a+b+1)/(3b)),1−((a+b+1)/(3b)))  +β(((a+1)/(3b)),1−((a+1)/(3b)))=π((1/(sin(((π(a+1))/(3b)))))+(1/(sin((π/(3b))(a+b+1))))

ifb0=x2bxb+11f(x)=xax2bxb+1xaintegrableifa+1>0a>1=inx2bxb+1x2bf(x)xa2bintegrablif2ba>12b>a+1sinceb>02b∣>∣a+1b<0x2bxb+1x2binzerof(x)xa2bintegrabla2b>1inf(x)=∼xa[integrablifa<12b<a+1<0⇒∣2b∣>∣a+1(a,b)R2b∣>∣a+1f(x)=0xax2bxb+1dx=0xa(xb+1)x3b+1dxx3b=t=0ta+b3b+ta3b1+t.t13b11+tdt=0ta+b+13b1+ta+13b11+t=β(a+b+13b,1a+b+13b)+β(a+13b,1a+13b)=π(1sin(π(a+1)3b)+1sin(π3b(a+b+1))

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