View Full Version : 3x + 2y + 4x + 5y, 5m + 2n - 3m + 6n: plz explain what to do

I've just been given this homework

3x + 2y + 4x + 5y

5m + 2n - 3m + 6n

Could someone explain what I have to do. There's more but I figure if someone could help me with the basics I might be able to do the others.

Thanks

a stumped 12year old

THis is what I think I should do on the first question. Add the x's and the y's together

3x + 2y +4x + 5y

Add 3x + 4x = 7x

and 2y + 5y = 7y

so the answer is 7x 7y I think

With the next questions there's a minus between the 2 groups

5m +2n - 3m + 6n with this one I'm not sure whether | add the m's and the n's together then subtract them from each other.

I've just read a couple of the other posters and gather you like it if we have a go and you can see what we're trying to do.

thanks

dmp

Subhotosh Khan

10-20-2008, 01:35 PM

Hi,

I've just been given this homework

What is the topic that is being covered in your class now?

On the top of the assignment - it should say something like - Simplify

3x + 2y + 4x + 5y

5m + 2n - 3m + 6n

Could someone explain what I have to do. There's more but I figure if someone could help me with the basics I might be able to do the others.

Thanks

a stumped 12year old

To start you off on the road to simplification - I'll do a similar problem.

Simplify:

10x + 12 y - 5z - 3x - 5y + 3z - 6x + 2y + 8z

First you collect like terms - in this case, one of those groups would be terms that have x's, another one of those groups would be terms that have y's andthe last group would be terms that have z's. I put parenthesis around these groups - just for convenienceThen:

= (10x - 3x - 6x) + (12y - 5y + 2y) + (-5z + 3z + 8z)

= (1x) + (9y) + (6z)

= x + 9y + 6z

Get it ...

If not look at the example problems worked out in your textbook. Then write back - showing your work and exactly where you are stuck, so that we know where to begin to help you.

Loren

10-20-2008, 01:38 PM

Your first job is to read the instructions. What do they tell you to do?

When posting a question it helps if you copy the instructions and problems word for word and show us your work.

Subhotosh Khan

10-20-2008, 01:39 PM

THis is what I think I should do on the first question. Add the x's and the y's together

3x + 2y +4x + 5y

Add 3x + 4x = 7x

and 2y + 5y = 7y

so the answer is 7x + 7y ........... correct (after putting the sign as indicated)

I think

With the next questions there's a minus between the 2 groups

5m +2n - 3m + 6n with this one I'm not sure whether | add the m's and the n's together then subtract them from each other.

5m - 3m = 2m

2n + 6n = 8n

Now finish it off like before.....

I've just read a couple of the other posters and gather you like it if we have a go and you can see what we're trying to do.

thanks

dmp

And pay heed to "Loren"s post - always copy problem completely and correctly.

Hi Subhotosh and Loren,

Thanks for your replys.

On the second question you say finish is off like the other one.

Do you use the + or - symbol that is in the middle of the equation ie.

So should it look like 2m - 8n as that is the middle symbol ( 5m + 2n - 3m + 6n)

Thanks

dmp

Subhotosh Khan

10-20-2008, 04:05 PM

Work through the example I have shown you - it should be clear.

Look at the example problems in your book - you should find worked out problems there to guide you.

Denis

10-21-2008, 12:38 AM

Do you use the + or - symbol that is in the middle of the equation ie.

So should it look like 2m - 8n as that is the middle symbol ( 5m + 2n - 3m + 6n)

dmp, you seem quite "bright" for a 12 years old; and your English is better than many older

students we get here :wink:

Now, relax a bit; the "m's" and "n's" shown in your expression could just as well be "apples" and "oranges";

like: 5 apples + 2 oranges - 3 apples + 6 oranges ; you can tell right away that you have 2 apples left,

and 8 oranges, right? SIMPLY put the same fruits together: 5 apples - 3 apples and 2 oranges + 6 oranges.

What's "in the middle" and wether it's + or - is of no importance: just use what's there.

The expression simply happens to be written this way:

5m + 2n - 3m + 6n

Could be written in any order, like:

5m + 6n + 2n - 3m

6n - 3m + 2n + 5m .... and other ways...

The trick is put the same variables together:

5m-3m + 2n+6n ; then it's simply:

2m + 8n ... or 2 apples and 8 oranges :idea:

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