定積分・広義積分計算機
定積分と広義積分を手順を追って計算する
この計算機は、定積分(すなわち上下限のある積分)を、広義積分も含めて、解法手順を示しながら計算を試みます。
Solution
Your input: calculate $$$\int_{1}^{e}\left( \ln{\left(x \right)} \right)dx$$$
First, calculate the corresponding indefinite integral: $$$\int{\ln{\left(x \right)} d x}=x \left(\ln{\left(x \right)} - 1\right)$$$ (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.
$$$\left(x \left(\ln{\left(x \right)} - 1\right)\right)|_{\left(x=e\right)}=0$$$
$$$\left(x \left(\ln{\left(x \right)} - 1\right)\right)|_{\left(x=1\right)}=-1$$$
$$$\int_{1}^{e}\left( \ln{\left(x \right)} \right)dx=\left(x \left(\ln{\left(x \right)} - 1\right)\right)|_{\left(x=e\right)}-\left(x \left(\ln{\left(x \right)} - 1\right)\right)|_{\left(x=1\right)}=1$$$
Answer: $$$\int_{1}^{e}\left( \ln{\left(x \right)} \right)dx=1$$$