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Question Number 50426 by Abdo msup. last updated on 16/Dec/18
study the convergence of   U_n =((2/π) ∫_0 ^(π/2) (sinx)^(1/n) )^n
studytheconvergenceofUn=(2π0π2(sinx)1n)n
Answered by tanmay.chaudhury50@gmail.com last updated on 17/Dec/18
(1/π)×2∫_0 ^(π/2) sinx)^(2×(((1+n)/(2n)))−1) (cosx)^(2×(1/2)−1) dx  formula 2∫_0 ^(π/2) sin^(2p−1) xcos^(2q−1) xdx  =((⌈(p)⌈q))/(⌈p+q)))  so (1/π)×((⌈(((1+n)/(2n)))×⌈((1/2)))/(⌈(((1+n)/(2n))+(1/2))))  =(1/( (√π)))×((⌈((1/(2n))+(1/2)))/(⌈((1/(2n))+1)))  wait...
1π×20π2sinx)2×(1+n2n)1(cosx)2×121dxformula20π2sin2p1xcos2q1xdx=(p)q)p+q)so1π×(1+n2n)×(12)(1+n2n+12)=1π×(12n+12)(12n+1)wait
Answered by tanmay.chaudhury50@gmail.com last updated on 17/Dec/18
Another approach...   1≥sinx≥0  1≥(sinx)^(1/n) ≥0  (2/π)×∫_0 ^(π/2) 1×dx≥(2/π)∫_0 ^(π/2) (sinx)^(1/n) dx≥(2/π)∫_0 ^(π/2) 0×dx  2≥(2/π)∫_0 ^(π/2) (sinx)^(1/n) dx≥0  2^n ≥[(2/π)∫_0 ^(π/2)  (sinx)^(1/n) dx]^n ≥0
Anotherapproach1sinx01(sinx)1n02π×0π21×dx2π0π2(sinx)1ndx2π0π20×dx22π0π2(sinx)1ndx02n[2π0π2(sinx)1ndx]n0

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