Integral de xcos(kx) dx
Solución
Respuesta (Indefinida)
[src]
// 2 \
|| x |
|| -- for k = 0|
|| 2 |
/ || | // x for k = 0\
| ||/-cos(k*x) | || |
| x*cos(k*x) dx = C - |<|---------- for k != 0 | + x*|
$$\int x \cos{\left(k x \right)}\, dx = C + x \left(\begin{cases} x & \text{for}\: k = 0 \\\frac{\sin{\left(k x \right)}}{k} & \text{otherwise} \end{cases}\right) - \begin{cases} \frac{x^{2}}{2} & \text{for}\: k = 0 \\\frac{\begin{cases} - \frac{\cos{\left(k x \right)}}{k} & \text{for}\: k \neq 0 \\0 & \text{otherwise} \end{cases}}{k} & \text{otherwise} \end{cases}$$
/ 1 cos(pi*k) pi*sin(pi*k)
|- -- + --------- + ------------ for And(k > -oo, k < oo, k != 0)
| 2 2 k
| k k
<
| 2
| pi
| --- otherwise
\ 2
$$\begin{cases} \frac{\pi \sin{\left(\pi k \right)}}{k} + \frac{\cos{\left(\pi k \right)}}{k^{2}} - \frac{1}{k^{2}} & \text{for}\: k > -\infty \wedge k < \infty \wedge k \neq 0 \\\frac{\pi^{2}}{2} & \text{otherwise} \end{cases}$$
=
/ 1 cos(pi*k) pi*sin(pi*k)
|- -- + --------- + ------------ for And(k > -oo, k < oo, k != 0)
| 2 2 k
| k k
<
| 2
| pi
| --- otherwise
\ 2
$$\begin{cases} \frac{\pi \sin{\left(\pi k \right)}}{k} + \frac{\cos{\left(\pi k \right)}}{k^{2}} - \frac{1}{k^{2}} & \text{for}\: k > -\infty \wedge k < \infty \wedge k \neq 0 \\\frac{\pi^{2}}{2} & \text{otherwise} \end{cases}$$
Piecewise((-1/k^2 + cos(pi*k)/k^2 + pi*sin(pi*k)/k, (k > -oo)∧(k < oo)∧(Ne(k, 0))), (pi^2/2, True))
Estos ejemplos se pueden aplicar para introducción de los límites de integración inferior y superior.