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Evaluating a variable expression

rodgerst414

New member
Feb 11, 2013
8
a=4,b=3 and c=-2

5ab/12-2cb:confused:
 

MarkFL

Administrator
Staff member
Feb 24, 2012
13,775
As posted, it is hard to tell if you mean:

$\displaystyle \frac{5ab}{12}-2cb$

or

$\displaystyle \frac{5ab}{12-2cb}$

Until you learn to use $\LaTeX$, I recommend you use bracketing symbols to make it clear exactly what the denominator is.

If the first choice above is what you intend, then you could type (5ab/12) - 2cb, and if the second choice is what you intend, then you could type (5ab)/(12 - 2cb).

Do you see how that removes the potential ambiguity?
 

rodgerst414

New member
Feb 11, 2013
8
As posted, it is hard to tell if you mean:

$\displaystyle \frac{5ab}{12}-2cb$

or

$\displaystyle \frac{5ab}{12-2cb}$

Until you learn to use $\LaTeX$, I recommend you use bracketing symbols to make it clear exactly what the denominator is.

If the first choice above is what you intend, then you could type (5ab/12) - 2cb, and if the second choice is what you intend, then you could type (5ab)/(12 - 2cb).

Do you see how that removes the potential ambiguity?
it is the first one i just don't know how to put them in the calculator or write them on here.
 

MarkFL

Administrator
Staff member
Feb 24, 2012
13,775
Okay, you have technically written it correctly then, but there are so many students who would write what you did when they mean the second choice, that it is best to make sure.

Now, given what I told you in your first topic, what do you think you need to do here as the first step?
 

rodgerst414

New member
Feb 11, 2013
8
it is the first one i just don't know how to put them in the calculator or write them on here.
It is the first on you wrote how do you put into a calculator.
 

rodgerst414

New member
Feb 11, 2013
8
Okay, you have technically written it correctly then, but there are so many students who would write what you did when they mean the second choice, that it is best to make sure.

Now, given what I told you in your first topic, what do you think you need to do here as the first step?
Sorry but this is my first time to do these problems i don't understand.I quit school at a younger age. i am 41 first time in college.This is this the class they put me in.Can you recommend some books for me to learn these kinds of problems.
 

MarkFL

Administrator
Staff member
Feb 24, 2012
13,775
We really don't need a calculator for this. What we want to do is use the values we are given for the variables and plug them into the expression. Can you write the expression with the numbers put in to replace the variables?
 

MarkFL

Administrator
Staff member
Feb 24, 2012
13,775
...Can you recommend some books for me to learn these kinds of problems.
I think you have made a great start...you have come to a wonderful forum to get help, and I think once you get the hang of the procedure for these, you will understand what you need to do for other similar problems.

Books are good, but the feedback you get from helpers on a forum is much better.(Yes)