Question
Mathematics Question on Definite Integral
If
n(2n+1)∫01(1−xn)2ndx=1177∫01(1−xn)2n+1dx
,then n ∈ N is equal to ______.
Answer
The correct answer is 24
∫01(1−xn)2n+1dx=∫01(1−xn)2n+1dx
=[(1−xn)2n+1⋅x]01−∫01x⋅(2n+1)(1−xn)2n⋅(−nxn−1)dx
=n(2n+1)∫01(1−(1−xn))(1−xn)2ndx
=n(2n+1)∫01(1−xn)2ndx−n(2n+1)∫01(1−xn)2n+1dx
(1+n(2n+1))∫01(1−xn)2n+1dx=n(2n+1)∫01(1−xn)2ndx
(2n2+n+1)∫01(1−xn)2n+1dx=1177∫01(1−xn)2n+1dx
∴ 2 n 2 + n + 1 = 1177
2 n 2 + n – 1176 = 0
∴n=24or−249
∴ n = 24