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#1 Re: Help Me ! » Proving! » 2010-11-30 02:22:46

ampohmeow

Bob,

=>             -ab     +[ ab + a(-b) ] = -ab + 0   adding on the left of the expression

what property you used here? can also be like

[ab + a(-b)] + (-ab) = 0 + (-ab)    Addition Property of Equality

are they just the same?

#2 Re: Help Me ! » Proving! » 2010-11-30 02:17:12

ampohmeow

hi

a = -a

add 'a' to each side

2a = 0

Now, do you have a theorem that allows you to conclude a = 0 from this ?

( I ask this because when, you are deducing properties of the real number system from basic axioms, you have to 'prove' everything else.)

Bob

How to show that if 2a = 0, then a = 0, i don't have here any theorem or axioms that will support the statement.

#3 Re: Help Me ! » Proving! » 2010-11-30 01:49:33

ampohmeow

hi,

take a look

#1 problem

So,

ab + a(-b) = ab + a(-b)     Reflexive Property of Equality
                = a[b+(-b)]      Distributive Law
                = a(0)              Additive Inverse
                = 0                  Zero Product Property

if

ab + a(-b)             = 0         
ab + a(-b) + (-ab) = 0 + (-ab)    Addition Property of Equality
[ab+(-ab)] + a(-b) = 0 + (-ab)    Associative Property
             0 + a(-b)  = 0 + (-ab)   Additive Inverse

then
                   a(-b)  = -ab            Additive Identity

#4 Re: Help Me ! » Proving! » 2010-11-30 00:09:04

ampohmeow
bob bundy wrote:

hi

I had an idea then decided it was wrong so I've deleted it.  Sorry!

I'll come back later when I've got more time for this.

Bob

thanks Bob, kindly check also my answer for #1.

#5 Re: Help Me ! » Proving! » 2010-11-29 22:49:00

ampohmeow

anyone can help me on this?

#6 Re: Help Me ! » Proving! » 2010-11-29 02:39:00

ampohmeow

Is my proof for #1 correct?


2) Explain why 0 is the only real number which is its own additive inverse, that is, show that if a = (-a), then a = 0.

give me idea of how to prove #2, thanks.

#7 Re: Help Me ! » Proving! » 2010-11-29 01:58:57

ampohmeow
JaneFairfax wrote:

You are making a big mess there. What you need to do is start with the expression

You want to show that it is equal to 0. Using the distributive law gives

Can you carry on from here? What is b + (−b)?

if

ab + a(-b) = ab + a(-b)     Reflexive Property of Equality (is my starting equation correct???)
                = a[b+(-b)]      Distributive Law
                = a(0)              Additive Inverse
                = 0                  Zero Product Property

then

a(-b)         = -ab               Addition Property of Equality

#8 Re: Introductions » Hello everyone! » 2010-11-29 01:22:53

ampohmeow
ganesh wrote:

Hi Jmark,

Welcome to the forum!

thanks!

#9 Re: Help Me ! » Proving! » 2010-11-29 01:21:48

ampohmeow
JaneFairfax wrote:

Show that
(use the distributive law).

thanks a lot

ok let me try

ab + -(ab) = 0                     existence of additive inverse?
ab + (-b)a = [b + (-b)] a      by distributive law
ab + (-b)a = 0(a)                 additive inverse
ab + (-b)a = 0                     zero product property?

therefore by uniqueness of inverse, -ab = (-b)a?


ahm i'm not sure with this sad

#10 Introductions » Hello everyone! » 2010-11-29 00:20:49

ampohmeow
Replies: 5

Hi,



This is Jmark from Philippines.

I love this forum it helps a lot.

Math is Fun!



Forumer,

Jmark

#11 Re: Help Me ! » about SET.. » 2010-11-29 00:11:59

ampohmeow

Is it true that the subset of any set is 2^n, where n is the number of elements?

#12 Help Me ! » Proving! » 2010-11-28 23:58:06

ampohmeow
Replies: 21

help me with this one;

1) Prove that a(-b) = -ab, for any real number a and b.

2) Explain why 0 is the only real number which is its own additive inverse, that is, show that if a = (-a), then a = 0.


thanks.

#13 Re: Help Me ! » about SET.. » 2010-11-28 23:40:34

ampohmeow

thanks a lot.

God Bless and more Power!

#14 Help Me ! » about SET.. » 2010-11-28 03:55:18

ampohmeow
Replies: 4

i'm trying to answer this question,

1)How many subsets does the empty set have? What can you say about a set A if it has only one subset?

2) Explain what is meant by the statement. "The empty set is the identity with respect to the operation of set union".

thanks!

#15 Re: Help Me ! » What is Factogon? » 2010-11-08 22:09:57

ampohmeow

Guys thank you for all the reply, I appreciated it a lot.

Same with me here, I didn't heard that word before. I don't think so if the teacher who gave this project, don't know anything about the subject matter but instead trying to get more information about it that's why he gave it as a project.

Thanks guys. God bless and more Power!

#16 Re: Help Me ! » What is Factogon? » 2010-11-07 02:57:28

ampohmeow

Thanks for the reply.

Sir this was also asked in Yahoo but there's no answer and i think i'm not the only one have this kind of problem because many were asking in Yahoo.

Is this some kind of new term in Mathematics?

#17 Help Me ! » What is Factogon? » 2010-11-07 00:38:34

ampohmeow
Replies: 6

I've searched the net but there's no word factogon found.

This is our project in Math.

Help me thanks.

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