Řešení - Derivative

Applying the product rule of derivatives.

$$\frac{d}{dx}\left[xy\right]=\frac{d}{dx}\left[x\right]\times y+x\times \frac{d}{dx}\left[y\right]$$

The derivative of a variable with respect to itself is always equal to one.

$$\frac{d}{dx}\left[x\right]\times y+x\times \frac{d}{dx}\left[y\right]=1y+x\times \frac{d}{dx}\left[y\right]$$

Multiplying a number by one, which does not change its value.

$$1y+x\times \frac{d}{dx}\left[y\right]=y+x\times \frac{d}{dx}\left[y\right]$$