# Integralrechner (Stammfunktionsrechner) mit Schritten

Dieser Online-Rechner versucht, das unbestimmte Integral (Stammfunktion) der gegebenen Funktion mit angezeigten Schritten zu finden.

Enter a function:

Integrate with respect to:

Please write without any differentials such as dx, dy etc.

For definite integral, see definite integral calculator.

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## Solution

Your input: find $\int{x \cos{\left(x^{2} \right)} d x}$

Let $u=x^{2}$.

Then $du=\left(x^{2}\right)^{\prime }dx = 2 x dx$ (steps can be seen here), and we have that $x dx = \frac{du}{2}$.

The integral becomes

$$\color{red}{\int{x \cos{\left(x^{2} \right)} d x}} = \color{red}{\int{\frac{\cos{\left(u \right)}}{2} d u}}$$

Apply the constant multiple rule $\int c f{\left(u \right)}\, du = c \int f{\left(u \right)}\, du$ with $c=\frac{1}{2}$ and $f{\left(u \right)} = \cos{\left(u \right)}$:

$$\color{red}{\int{\frac{\cos{\left(u \right)}}{2} d u}} = \color{red}{\left(\frac{\int{\cos{\left(u \right)} d u}}{2}\right)}$$

The integral of the cosine is $\int{\cos{\left(u \right)} d u} = \sin{\left(u \right)}$:

$$\frac{\color{red}{\int{\cos{\left(u \right)} d u}}}{2} = \frac{\color{red}{\sin{\left(u \right)}}}{2}$$

Recall that $u=x^{2}$:

$$\frac{\sin{\left(\color{red}{u} \right)}}{2} = \frac{\sin{\left(\color{red}{x^{2}} \right)}}{2}$$

Therefore,

$$\int{x \cos{\left(x^{2} \right)} d x} = \frac{\sin{\left(x^{2} \right)}}{2}$$

$$\int{x \cos{\left(x^{2} \right)} d x} = \frac{\sin{\left(x^{2} \right)}}{2}+C$$
Answer: $\int{x \cos{\left(x^{2} \right)} d x}=\frac{\sin{\left(x^{2} \right)}}{2}+C$