Integral de $$$\sin{\left(x^{2} + y \right)}$$$ em relação a $$$x$$$

Encontre $$$\int \sin{\left(x^{2} + y \right)}\, dx$$$.

Reescreva o integrando:

$${\color{red}{\int{\sin{\left(x^{2} + y \right)} d x}}} = {\color{red}{\int{\left(\sin{\left(x^{2} \right)} \cos{\left(y \right)} + \sin{\left(y \right)} \cos{\left(x^{2} \right)}\right)d x}}}$$

Integre termo a termo:

$${\color{red}{\int{\left(\sin{\left(x^{2} \right)} \cos{\left(y \right)} + \sin{\left(y \right)} \cos{\left(x^{2} \right)}\right)d x}}} = {\color{red}{\left(\int{\sin{\left(x^{2} \right)} \cos{\left(y \right)} d x} + \int{\sin{\left(y \right)} \cos{\left(x^{2} \right)} d x}\right)}}$$

Aplique a regra do múltiplo constante $$$\int c f{\left(x \right)}\, dx = c \int f{\left(x \right)}\, dx$$$ usando $$$c=\cos{\left(y \right)}$$$ e $$$f{\left(x \right)} = \sin{\left(x^{2} \right)}$$$:

$$\int{\sin{\left(y \right)} \cos{\left(x^{2} \right)} d x} + {\color{red}{\int{\sin{\left(x^{2} \right)} \cos{\left(y \right)} d x}}} = \int{\sin{\left(y \right)} \cos{\left(x^{2} \right)} d x} + {\color{red}{\cos{\left(y \right)} \int{\sin{\left(x^{2} \right)} d x}}}$$

Esta integral (Integral Seno de Fresnel) não possui forma fechada:

$$\cos{\left(y \right)} {\color{red}{\int{\sin{\left(x^{2} \right)} d x}}} + \int{\sin{\left(y \right)} \cos{\left(x^{2} \right)} d x} = \cos{\left(y \right)} {\color{red}{\left(\frac{\sqrt{2} \sqrt{\pi} S\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right)}{2}\right)}} + \int{\sin{\left(y \right)} \cos{\left(x^{2} \right)} d x}$$

Aplique a regra do múltiplo constante $$$\int c f{\left(x \right)}\, dx = c \int f{\left(x \right)}\, dx$$$ usando $$$c=\sin{\left(y \right)}$$$ e $$$f{\left(x \right)} = \cos{\left(x^{2} \right)}$$$:

$$\frac{\sqrt{2} \sqrt{\pi} \cos{\left(y \right)} S\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right)}{2} + {\color{red}{\int{\sin{\left(y \right)} \cos{\left(x^{2} \right)} d x}}} = \frac{\sqrt{2} \sqrt{\pi} \cos{\left(y \right)} S\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right)}{2} + {\color{red}{\sin{\left(y \right)} \int{\cos{\left(x^{2} \right)} d x}}}$$

Esta integral (Integral de Fresnel do cosseno) não possui forma fechada:

$$\sin{\left(y \right)} {\color{red}{\int{\cos{\left(x^{2} \right)} d x}}} + \frac{\sqrt{2} \sqrt{\pi} \cos{\left(y \right)} S\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right)}{2} = \sin{\left(y \right)} {\color{red}{\left(\frac{\sqrt{2} \sqrt{\pi} C\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right)}{2}\right)}} + \frac{\sqrt{2} \sqrt{\pi} \cos{\left(y \right)} S\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right)}{2}$$

Portanto,

$$\int{\sin{\left(x^{2} + y \right)} d x} = \frac{\sqrt{2} \sqrt{\pi} \sin{\left(y \right)} C\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right)}{2} + \frac{\sqrt{2} \sqrt{\pi} \cos{\left(y \right)} S\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right)}{2}$$

Simplifique:

$$\int{\sin{\left(x^{2} + y \right)} d x} = \frac{\sqrt{2} \sqrt{\pi} \left(\sin{\left(y \right)} C\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right) + \cos{\left(y \right)} S\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right)\right)}{2}$$

Adicione a constante de integração:

$$\int{\sin{\left(x^{2} + y \right)} d x} = \frac{\sqrt{2} \sqrt{\pi} \left(\sin{\left(y \right)} C\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right) + \cos{\left(y \right)} S\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right)\right)}{2}+C$$

$$$\int \sin{\left(x^{2} + y \right)}\, dx = \frac{\sqrt{2} \sqrt{\pi} \left(\sin{\left(y \right)} C\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right) + \cos{\left(y \right)} S\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right)\right)}{2} + C$$$A