# Equality

by Cornraker
Tags: equality
 P: 24 1. The problem statement, all variables and given/known data So i get a home work problem that goes like this. ab+ac/a=b+ac. is the left side of the equation not equal to or equal to the right side?
 Admin P: 21,706 $$ab + \frac {ac} {a} = b + ac$$ or $$\frac {ab + ac} {a} = b + ac$$ ?
 P: 24 thanks Borek. My answers in the back of my textbook say it is not equal but i can't figure out why. ill ask my teacher tommorow i just wanted to get some help ahead of time. thanks
Mentor
P: 19,743

## Equality

 Quote by Cornraker thanks Borek. My answers in the back of my textbook say it is not equal but i can't figure out why. ill ask my teacher tommorow i just wanted to get some help ahead of time. thanks
Please read what Borek wrote. He's not giving you and answer; he's trying to understand what you meant. Please use parentheses to indicate which expressions are in the numerator on the left side.
 P: 1,077 either way they arent equal. so what does it matter
Mentor
P: 19,743
 Quote by dacruick either way they arent equal. so what does it matter
It's always better to know exactly what the problem is than to not know, that's why it matters.
P: 1,077
 Quote by Mark44 It's always better to know exactly what the problem is than to not know, that's why it matters.
But it doesn't matter with respect to his answer. Neither of them are equal. If the problem represented something physical then i understand that.'

And for the record, you support your statements poorly. Why should i know this? oh because its better to know then not to know?
 PF Patron P: 1,930 Well, the second equation is equal when a=1... And the first equation is equal when a=1 and b=c. They aren't necessarily unequal.
Mentor
P: 19,743
 Quote by dacruick But it doesn't matter with respect to his answer.
Yes, that is true. On the other hand, a large number of posters in this forum present problems that are ambiguous. For my part, I would rather make these posters aware that their problems can be interpreted in multiple ways than work all possible variants of these problems.
 Quote by dacruick Neither of them are equal. If the problem represented something physical then i understand that.'
I don't see how that makes a difference.
 Quote by dacruick And for the record, you support your statements poorly. Why should i know this? oh because its better to know then not to know?
So are you saying that it is not better to know exactly what the problem is?
 P: 24 Ok I looked at it again and I do realize he was just asking which form of the problem I meant and the second one is the correct one. I still do not understand why they are unequal.
 Mentor P: 19,743 $$\frac {ab + ac} {a} = \frac{a(b + c)}{a} = b + c \neq b + ac$$ The first and last expressions above are not identically equal. They are conditionally equal for some values of the variables, such as a = 1.
 P: 1,077 Cornraker, just because they are equal for some values does not in a sense warrant that equal sign.

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