SOLUTION: Please help me prove: -a = (-1)*a Thank you.

Algebra ->  Proofs -> SOLUTION: Please help me prove: -a = (-1)*a Thank you.      Log On


   

Question 569226: Please help me prove:
-a = (-1)*a

Thank you.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
-a = (-1)*a
---
You need to show the (-1)a is the additive inverse of "a".
-------------------------
a + (-1)a = (1+(-1))a ; Distributive Law
= 0*a = 0 ; Definition of additive inverse.
---
Therefore (-1)a is the additive inverse of a ; Definition of additive inverse.
-------------------------
Therefore (-1)a = -a ; Def. of equality
==========================================
Cheers,
Stan H.
==================