# Mean Energy Fluctuations

Hello!

I'm getting muddled with the notation in my notes, in which I have

$$\overline{(E-\overline{E})(P-\overline{P})}$$

From which you can get

$$\overline{EP} - \overline{E} \ \overline{P}$$

I can see where these come from, but not where the

$$\overline{E \overline{P}} - \overline{\overline{E} P}$$

terms vanished to?

Last edited:

Bill_K
$$\overline{EP} - \overline{E} \ \overline{P}$$

I can see where these come from, but not where the

$$\overline{E \overline{P}} - \overline{\overline{E} P}$$

terms vanished to?
$$\overline{E \overline{P}} = \overline{\overline{E} P} = \overline{E} \ \overline{P}$$

so they cancel out.

Great thank you!