# A short problem, help me please!

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• Sep 5th 2006, 11:06 AM
diamondfox
A short problem, help me please!
Right, my first post, I'll say, "hi" to everybody for a start.

Hello.

Now for the problem, I would like somebody to come up to me with an answer fast since I only have 4 hours left. = (.

!!!!The numbers in the first statement in the bracket are, powers!!!!

1(2') - 1(2') = 1-1
(1+1)(1-1) = 1-1
1+1 = 1
2 = 1

Now according to our math teacher, the first statement is correct while the other 3 are wrong. :eek:

Now help me??!! =(
• Sep 5th 2006, 01:53 PM
Nick744
Okay

$\displaystyle 1^2 - 1^2 = 1 - 1 = 0$
So to prove this,
$\displaystyle 1^2 - (x)^2 = 1 - x^2$
Sub x = -1
$\displaystyle 1^2 - (-1)^2 = 1-1 = 0$
And if you solve that equation...
$\displaystyle 1 - x^2 = 0$
$\displaystyle x^2 = 1$
Therefore,
$\displaystyle x = +-\sqrt{1}$
which is,
$\displaystyle x = +- 1$

That tells us that if x = + or - 1, the equation will equal to 0...as it does!

With those other two statements...im not quite sure what they are (e.g if they are possible solution from your text book (like multiple choice) or some other wierd expansion...anyhow)

The second statement you definetly cant get from the first...but it equals to zero.

Hope this helped
• Sep 5th 2006, 01:59 PM
Quick
Quote:

Originally Posted by diamondfox

1(2') - 1(2') = 1-1
(1+1)(1-1) = 1-1
1+1 = 1
2 = 1

Now according to our math teacher, the first statement is correct while the other 3 are wrong. :eek:

Now help me??!! =(

What is your teacher talking about??? Both the first and second statements are correct, maybe there's a typo?
• Sep 5th 2006, 02:03 PM
CaptainBlack
Quote:

Originally Posted by diamondfox
Right, my first post, I'll say, "hi" to everybody for a start.

Hello.

Now for the problem, I would like somebody to come up to me with an answer fast since I only have 4 hours left. = (.

!!!!The numbers in the first statement in the bracket are, powers!!!!

1(2') - 1(2') = 1-1

OK this is 0=0

Quote:

(1+1)(1-1) = 1-1
OK this is 2x0=0

Quote:

1+1 = 1
Does not follow as you just divided by 0 on both sides of the =,
which is not allowed.

RonL
• Sep 5th 2006, 02:13 PM
Quick
Ohhhhhhhhhhhhhh... I didn't realize it was the steps of his work