Integralen av $$$2 x^{3} - 3 x^{2} - 5$$$

Bestäm $$$\int \left(2 x^{3} - 3 x^{2} - 5\right)\, dx$$$.

Integrera termvis:

$${\color{red}{\int{\left(2 x^{3} - 3 x^{2} - 5\right)d x}}} = {\color{red}{\left(- \int{5 d x} - \int{3 x^{2} d x} + \int{2 x^{3} d x}\right)}}$$

Tillämpa konstantregeln $$$\int c\, dx = c x$$$ med $$$c=5$$$:

$$- \int{3 x^{2} d x} + \int{2 x^{3} d x} - {\color{red}{\int{5 d x}}} = - \int{3 x^{2} d x} + \int{2 x^{3} d x} - {\color{red}{\left(5 x\right)}}$$

Tillämpa konstantfaktorregeln $$$\int c f{\left(x \right)}\, dx = c \int f{\left(x \right)}\, dx$$$ med $$$c=3$$$ och $$$f{\left(x \right)} = x^{2}$$$:

$$- 5 x + \int{2 x^{3} d x} - {\color{red}{\int{3 x^{2} d x}}} = - 5 x + \int{2 x^{3} d x} - {\color{red}{\left(3 \int{x^{2} d x}\right)}}$$

Tillämpa potensregeln $$$\int x^{n}\, dx = \frac{x^{n + 1}}{n + 1}$$$ $$$\left(n \neq -1 \right)$$$ med $$$n=2$$$:

$$- 5 x + \int{2 x^{3} d x} - 3 {\color{red}{\int{x^{2} d x}}}=- 5 x + \int{2 x^{3} d x} - 3 {\color{red}{\frac{x^{1 + 2}}{1 + 2}}}=- 5 x + \int{2 x^{3} d x} - 3 {\color{red}{\left(\frac{x^{3}}{3}\right)}}$$

Tillämpa konstantfaktorregeln $$$\int c f{\left(x \right)}\, dx = c \int f{\left(x \right)}\, dx$$$ med $$$c=2$$$ och $$$f{\left(x \right)} = x^{3}$$$:

$$- x^{3} - 5 x + {\color{red}{\int{2 x^{3} d x}}} = - x^{3} - 5 x + {\color{red}{\left(2 \int{x^{3} d x}\right)}}$$

Tillämpa potensregeln $$$\int x^{n}\, dx = \frac{x^{n + 1}}{n + 1}$$$ $$$\left(n \neq -1 \right)$$$ med $$$n=3$$$:

$$- x^{3} - 5 x + 2 {\color{red}{\int{x^{3} d x}}}=- x^{3} - 5 x + 2 {\color{red}{\frac{x^{1 + 3}}{1 + 3}}}=- x^{3} - 5 x + 2 {\color{red}{\left(\frac{x^{4}}{4}\right)}}$$

Alltså,

$$\int{\left(2 x^{3} - 3 x^{2} - 5\right)d x} = \frac{x^{4}}{2} - x^{3} - 5 x$$

Förenkla:

$$\int{\left(2 x^{3} - 3 x^{2} - 5\right)d x} = x \left(\frac{x^{3}}{2} - x^{2} - 5\right)$$

Lägg till integrationskonstanten:

$$\int{\left(2 x^{3} - 3 x^{2} - 5\right)d x} = x \left(\frac{x^{3}}{2} - x^{2} - 5\right)+C$$

$$$\int \left(2 x^{3} - 3 x^{2} - 5\right)\, dx = x \left(\frac{x^{3}}{2} - x^{2} - 5\right) + C$$$A