Problems from the very beginning ? (Serge Langs Basic Math: 3 = - (-3) or 5 = - (-5))

[Inkhole]

Hello all
I missed out at math at school (due to being an idiot) so I am now starting from scratch at 58. I had seen that Serge Langs Basic M<athematics was a good book but I am already stuck at the very beginning which is rather disheartening. I have attached the two sections from relavent pages and just need an explanation of what is meant by:

3 = - (-3)
or
5 = - (-5)

Thank you in advance for any help or ideas
Ian

 

[blamocur]

need an explanation of what is meant by:

3 = - (-3)
or
5 = - (-5)

Not sure where you are stuck, but the attached pages illustrate that operation of negation can be interpreted as a reflection relative to 0. If you reflect something twice you get back to where you started. Does this make sense?

 

[Steven G]

When you put negative sign, - , in front of a number then the sign of the number changes. If you put a neg sign in front of 5 you get -5. If you put a neg sign in front of -5 you get 5, that is -(-5) = 5

 

[Inkhole]

Not sure where you are stuck, but the attached pages illustrate that operation of negation can be interpreted as a reflection relative to 0. If you reflect something twice you get back to where you started. Does this make sense?

Thank you for taking the time to respond. Yes, that does make sense; I think it is jst how it was written in the book that confused me.

 

[Inkhole]

When you put negative sign, - , in front of a number then the sign of the number changes. If you put a neg sign in front of 5 you get -5. If you put a neg sign in front of -5 you get 5, that is -(-5) = 5

Thank you for taking time out to respond. The way you have put it makes perfect sense, unlike the book which had me stumped.