grandes-ecoles 2024 Q14

grandes-ecoles · France · mines-ponts-maths1__mp Sequences and Series Evaluation of a Finite or Infinite Sum
Show that for all $n \in \mathbf { N } ^ { * }$:
$$\int _ { \frac { \pi } { 2 } + ( n - 1 ) \pi } ^ { \frac { \pi } { 2 } + n \pi } ( \cos ( t ) ) ^ { 2 p } \frac { \sin ( t ) } { t } \mathrm {~d} t = \int _ { 0 } ^ { \frac { \pi } { 2 } } ( \cos ( t ) ) ^ { 2 p } \frac { 2 ( - 1 ) ^ { n } t \sin ( t ) } { t ^ { 2 } - n ^ { 2 } \pi ^ { 2 } } \mathrm {~d} t$$
Show that for all $n \in \mathbf { N } ^ { * }$:

$$\int _ { \frac { \pi } { 2 } + ( n - 1 ) \pi } ^ { \frac { \pi } { 2 } + n \pi } ( \cos ( t ) ) ^ { 2 p } \frac { \sin ( t ) } { t } \mathrm {~d} t = \int _ { 0 } ^ { \frac { \pi } { 2 } } ( \cos ( t ) ) ^ { 2 p } \frac { 2 ( - 1 ) ^ { n } t \sin ( t ) } { t ^ { 2 } - n ^ { 2 } \pi ^ { 2 } } \mathrm {~d} t$$