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Question Number 45885 by Meritguide1234 last updated on 17/Oct/18

Commented by maxmathsup by imad last updated on 18/Oct/18

let A_n =∫_0 ^(π/2)  n(1−(sinx)^(1/n) )dx =∫_0 ^(π/2)   f_n (x)dx with f_n (x)=n(1−(sinx^(1/n) ))  but we have  (sinx)^(1/n)  =e^((1/n)ln(sinx)) =1+((ln(sinx))/n) +o((1/n)) ⇒  1−e^((1/n)ln(sinx)) =−((ln(sinx))/n) +o((1/n)) ⇒n(1−e^((ln(sinx))/n) )=−ln(sinx) +o(1) ⇒  f_n (x)=−ln(sinx)+o(1) ⇒lim_(n→+∞)  A_n = ∫_0 ^(π/2) −ln(sinx)dx  =−(−(π/2)ln(2))=(π/2)ln(2).

letAn=0π2n(1(sinx)1n)dx=0π2fn(x)dxwithfn(x)=n(1(sinx1n))butwehave(sinx)1n=e1nln(sinx)=1+ln(sinx)n+o(1n)1e1nln(sinx)=ln(sinx)n+o(1n)n(1eln(sinx)n)=ln(sinx)+o(1)fn(x)=ln(sinx)+o(1)limn+An=0π2ln(sinx)dx=(π2ln(2))=π2ln(2).

Commented by Meritguide1234 last updated on 19/Oct/18

nice approach

niceapproach

Commented by maxmathsup by imad last updated on 20/Oct/18

thank you sir.

thankyousir.

Answered by tanmay.chaudhury50@gmail.com last updated on 17/Oct/18

lim_(n→∞)  n∫_0 ^(π/2) {1−(sinx)^(1/n) }dx  lim_(n→∞)  n[∣x∣_0 ^(π/2) −∫_0 ^(π/2) sin^(2p−1) xcoz^(2q−1) x dx]  here 2p−1=(1/n)     2p=1+(1/n)    p=((n+1)/(2n))    2q−1=0    q=(1/2)    using gamma beta function  formula ∫_0 ^(π/2) sin^(2p−1) xcos^(2a−1) xdx=((⌈(p)⌈(q))/(2⌈(p+q)))    lim_(n→∞)  n[(π/2)−((⌈(p)⌈(q))/(2⌈(p+q)))]  lim_(n→∞)  n[(π/2)−((⌈(((n+1)/(2n)))⌈((1/2)))/(2⌈(((n+1)/(2n))+(1/2))))]  lim_(n→∞)  n[(π/2)−((⌈(1+((1−n)/(2n)))×(√π))/(2⌈(1+((n+1)/(2n))−(1/2))))   ]  lim_(n→∞) n[(π/2)−(((√π) ×⌈(1+((1−n)/(2n))))/(2⌈(1+(1/(2n)))))]

limnn0π2{1(sinx)1n}dxlimnn[x0π20π2sin2p1xcoz2q1xdx]here2p1=1n2p=1+1np=n+12n2q1=0q=12usinggammabetafunctionformula0π2sin2p1xcos2a1xdx=(p)(q)2(p+q)limnn[π2(p)(q)2(p+q)]limnn[π2(n+12n)(12)2(n+12n+12)]limnn[π2(1+1n2n)×π2(1+n+12n12)]limnn[π2π×(1+1n2n)2(1+12n)]

Commented by Meritguide1234 last updated on 18/Oct/18

not correct

notcorrect

Commented by tanmay.chaudhury50@gmail.com last updated on 18/Oct/18

yes i know the result is yet to come ...when n→∞  the results is ∞

yesiknowtheresultisyettocome...whenntheresultsis

Commented by Meritguide1234 last updated on 18/Oct/18

put n=1/t...then ans is ((π/2)ln2)

putn=1/t...thenansis(π2ln2)

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