I came out with the right answer, but did I work this out correctly?

-7y = 0

-7y/-7 = 0/-7

-y = 0

-y/-y = 0/-y

y=0

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- March 3rd 2006, 06:23 AMEuclid Alexandria-7y = 0
I came out with the right answer, but did I work this out correctly?

-7y = 0

-7y/-7 = 0/-7

-y = 0

-y/-y = 0/-y

y=0 - March 3rd 2006, 07:45 AMearbothQuote:

Originally Posted by**Euclid Alexandria**

you have made only a minor mistake:

-7y/-7 = 0/-7

y = 0

because -7y/-7 = +y the last two lines aren't necessary (and slightly wrong).

Greetings

EB - March 3rd 2006, 08:23 AMAradesh
also going from

and you then said

this is not equivalent to:

as you said.

you had

so what you want to do here to get the solution is divide both sides by

since it turns out

before you were trying to say which is which is undefined. - March 4th 2006, 07:45 AMEuclid Alexandria
Thanks, guys. I couldn't remember the rule for getting a negative variable to be positive. You always divide both sides by -1?

- March 4th 2006, 05:42 PMAradesh
you could either divide by -1, multiply by -1, the effect is the same. you don't tend to think of it as "multiplying/dividing by -1" though. you just change the sign of both sides. for instance if

then

you are simply changing the sign of both sides. you don't really need to explain yourself when doing that :)

likewise if you had

then changing the signs of each side gives:

however multiplying through by -1 is a more common way of thinking about it than dividing through by -1. - March 5th 2006, 03:50 AMtopsquarkQuote:

Originally Posted by**Aradesh**

-Dan