- #1

- 762

- 59

## Homework Statement

Having one of those days where nothing makes sense, here is the derivation:

how does he get the two circled terms from what he's derived above?

## Homework Equations

N/A

## The Attempt at a Solution

I tried substitution but get nowhere I just can't see how the early expressions help in getting the circled expressions.

once again, any pointers in the right direction would be appreciated