Kalkylator för bestämda och oegentliga integraler
Beräkna bestämda och oegentliga integraler steg för steg
Kalkylatorn försöker beräkna bestämda integraler (dvs. med integrationsgränser), inklusive oegentliga, och visar stegen.
Solution
Your input: calculate $$$\int_{-1}^{1}\left( \frac{2}{x^{2} + 1} \right)dx$$$
First, calculate the corresponding indefinite integral: $$$\int{\frac{2}{x^{2} + 1} d x}=2 \operatorname{atan}{\left(x \right)}$$$ (for steps, see indefinite integral calculator)
According to the Fundamental Theorem of Calculus, $$$\int_a^b F(x) dx=f(b)-f(a)$$$, so just evaluate the integral at the endpoints, and that's the answer.
$$$\left(2 \operatorname{atan}{\left(x \right)}\right)|_{\left(x=1\right)}=\frac{\pi}{2}$$$
$$$\left(2 \operatorname{atan}{\left(x \right)}\right)|_{\left(x=-1\right)}=- \frac{\pi}{2}$$$
$$$\int_{-1}^{1}\left( \frac{2}{x^{2} + 1} \right)dx=\left(2 \operatorname{atan}{\left(x \right)}\right)|_{\left(x=1\right)}-\left(2 \operatorname{atan}{\left(x \right)}\right)|_{\left(x=-1\right)}=\pi$$$
Answer: $$$\int_{-1}^{1}\left( \frac{2}{x^{2} + 1} \right)dx=\pi\approx 3.14159265358979$$$