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Question Number 173148 by JordanRoddy last updated on 07/Jul/22

    ∫_0 ^1 ^n (√x) (arcsin x) dx

01nx(arcsinx)dx

Answered by Mathspace last updated on 07/Jul/22

I_n =∫_0 ^1 (^n (√x))arcsinx dx we do  the changement arcsinx=t ⇒  x=sint and  I_n =∫_0 ^(π/2) (sint)^(1/n) t cost dt  =∫_0 ^(π/2) t(cost (sint)^(1/n) )dt  =[(t/(1+(1/n)))(sint)^(1+(1/n)) ]_0 ^(π/2)   −∫_0 ^(π/2) (n/(n+1))(sint)^(1+(1/n)) dt  ((πn)/(2(n+1)))−(n/(n+1))∫_0 ^(π/2) (sint)^(1+(1/n)) dt  we have ∫_0 ^(π/2) (cost)^(2p−1) .(sint)^(2q−1) dt  =B(ρ,q)=((Γ(ρ).Γ(q))/(Γ(ρ+q))) ⇒  2ρ−1=0 and 2q−1=1+(1/n)  ⇒ρ=(1/2) and q=1+(1/(2n))  ∫_0 ^(π/2) (sint)^(1+(1/n)) dt=((Γ((1/2))Γ(1+(1/(2n))))/(2Γ((1/2)+1+(1/(2n)))))  =((√π)/2)×((Γ(1+(1/(2n))))/(Γ((3/2)+(1/(2n))))) ⇒  I_n =((nπ)/(2(n+1)))−(n/(n+1)).((√π)/2)×((Γ(1+(1/(2n))))/(Γ((3/2)+(1/(2n)))))

In=01(nx)arcsinxdxwedothechangementarcsinx=tx=sintandIn=0π2(sint)1ntcostdt=0π2t(cost(sint)1n)dt=[t1+1n(sint)1+1n]0π20π2nn+1(sint)1+1ndtπn2(n+1)nn+10π2(sint)1+1ndtwehave0π2(cost)2p1.(sint)2q1dt=B(ρ,q)=Γ(ρ).Γ(q)Γ(ρ+q)2ρ1=0and2q1=1+1nρ=12andq=1+12n0π2(sint)1+1ndt=Γ(12)Γ(1+12n)2Γ(12+1+12n)=π2×Γ(1+12n)Γ(32+12n)In=nπ2(n+1)nn+1.π2×Γ(1+12n)Γ(32+12n)

Commented by Mathspace last updated on 07/Jul/22

sorry..∫_0 ^(π/2) (cost)^(2ρ−1) (sint)^(2q−1) dt  =(1/2)B(p,q)=((Γ(ρ).Γ(q))/(2Γ(ρ+q)))

sorry..0π2(cost)2ρ1(sint)2q1dt=12B(p,q)=Γ(ρ).Γ(q)2Γ(ρ+q)

Commented by Tawa11 last updated on 11/Jul/22

Great sir

Greatsir

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