- #1
chickensagan
- 8
- 0
Please may someone explain the last step of this proof for me? I can't see how it's done algebraically. Where does the second (x1-x2) go? Is it a mistake?
I've tried multiplying out -2 and everything else I could think of but to no avail.
Thank you.
I've tried multiplying out -2 and everything else I could think of but to no avail.
Thank you.