(Oral Mines-Ponts) Soient {\theta \in\,]0,\pi[}. On pose : {f(x)\!=\!\!\displaystyle\sum\limits_{n=1}^{+\infty }\dfrac{\cos n\theta}{n}x^{n}\,\text{et}\,g(x)\!=\!\!\displaystyle\sum\limits_{n=1}^{+\infty }\dfrac{\sin n\theta }{n}x^{n}}
|
(Oral Mines-Ponts) Soient {\theta \in\,]0,\pi[}. On pose : {f(x)\!=\!\!\displaystyle\sum\limits_{n=1}^{+\infty }\dfrac{\cos n\theta}{n}x^{n}\,\text{et}\,g(x)\!=\!\!\displaystyle\sum\limits_{n=1}^{+\infty }\dfrac{\sin n\theta }{n}x^{n}}
|