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- BarandaMan
- 2012-11-16 10:20:12
Wow, this is incredible. Thank you really. I don't know why people don't get taught stuff like this sometimes, or maybe I forgot, but never the underlying reasons for the rules it seems. This actually makes sense. Thank you. I don't think I will forget it again. I drew it out with three examples!! 
- bob bundy
- 2012-11-16 09:15:14
OK.
Take a look at the diagram
On the right I am trying to show that 3 < 9
When you multiply or divide by -1 it becomes -9 < -3
Make up your own example. When you multiply or divide by a negative it has the effect of reflecting in the 'y axis' so the inequality flips around.
Hope that makes sense.
Bob
- bob bundy
- 2012-11-16 09:09:06
Definitely a reason. Maths is like that !!!!!
Explanation coming up
Bob
- BarandaMan
- 2012-11-16 09:06:04
Thank you very very much indeed. The change of the inequality sign is what got me. Thank you for helping me.
This makes sense. With this rule though, I just must remember it, right? Does it exist for a reason? Or is it just one we must remember?
Thanks!!!!
- bob bundy
- 2012-11-16 08:56:54
hi BarandaMan
x by 5
Add 2z
take 6
divide by 2
I suspect you ran into difficulty because of this
take 2
divide by -2
when you multiply or divide by a negative amount you must reverse the inequality sign
Bob
If you want to explore this rule some more, post back.
hi bobbym, sorry didn't know you were posting too.
- BarandaMan
- 2012-11-16 08:54:09
Really?!
Can you please show me your working?
- bobbym
- 2012-11-16 08:50:59
Hi BarandaMan;
I am getting z > -2.
- BarandaMan
- 2012-11-16 08:40:55
Hey!
Hope you all are doing good.
I have
(6/5) > (2/5) - (2/5)z
I get this down to z > 2.
The answer says it should be, z < 2.
Please help me? Thank you!!!!