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# Maths help please...? Algebra. Grade - D watch

1. Erm... I'm slightly confused.. on this Question. And I was wondering if someone would be able to help me understand please?

So I had to simplify this Algebraic Expression - 7ab + 3ba

The ANS is 10ab. Which I don't understand why. Could someone please explain? What I don't understand is that there is 2 a's and 2 b's but when they simplified your not able to tell that their is two a's and two b's.

Thanks in advance xx
2. (Original post by Carrot_Cake_13)
Erm... I'm slightly confused.. on this Question. And I was wondering if someone would be able to help me understand please?

So I had to simplify this Algebraic Expression - 7ab + 3ba

The ANS is 10ab. Which I don't understand why. Could someone please explain? What I don't understand is that there is 2 a's and 2 b's but when they simplified your not able to tell that their is two a's and two b's.

Thanks in advance xx
I am assuming that is 7ab not -7ab as it reads!

If you have 7 of something and add 3 more then you get 10 of it.

ab = ba because the order of multiplication does not matter*.

* Anyone who mentions matrices here deserves a punch.
3. (Original post by Carrot_Cake_13)
Erm... I'm slightly confused.. on this Question. And I was wondering if someone would be able to help me understand please?

So I had to simplify this Algebraic Expression - 7ab + 3ba

The ANS is 10ab. Which I don't understand why. Could someone please explain? What I don't understand is that there is 2 a's and 2 b's but when they simplified your not able to tell that their is two a's and two b's.

Thanks in advance xx
If you think about multiplication, is the same as .

In the same way, since and just represent numbers, , or

So we can rewrite the expression as .

Now we have which if you carry out the addition, gives .
4. (Original post by Carrot_Cake_13)
Erm... I'm slightly confused.. on this Question. And I was wondering if someone would be able to help me understand please?

So I had to simplify this Algebraic Expression - 7ab + 3ba

The ANS is 10ab. Which I don't understand why. Could someone please explain? What I don't understand is that there is 2 a's and 2 b's but when they simplified your not able to tell that their is two a's and two b's.

Thanks in advance xx

Its like

5. (Original post by The Polymath)
...
You can get the multiplication sign in LaTeX by using \times. Using this symbol would make your post less confusing.

Edit: You already know!
6. (Original post by Mr M)
You can get the multiplication sign in LaTeX by using \times. Using this symbol would make your post less confusing.

Edit: You already know!
I'm a little rusty

Thanks though
7. (Original post by The Polymath)
Now we have which if you carry out the addition, gives .

Okay I'm fine with everything you explained up until the last sentence...

So...I understand to simplify you need to add the 7+3 which gives us the 10.
But if you add the ab + ba... Does it not give us 2 a's and 2 b's.
Yet in the answer there is only one a and one b represented - 10ab

I don't know if anything I said ^^ makes sense :/
8. (Original post by Carrot_Cake_13)
Okay I'm fine with everything you explained up until the last sentence...

So...I understand to simplify you need to add the 7+3 which gives us the 10.
But if you add the ab + ba... Does it not give us 2 a's and 2 b's.
Yet in the answer there is only one a and one b represented - 10ab

I don't know if anything I said ^^ makes sense :/
We got to , which I'm assuming you're okay with.

So you start with 7 lots of (ab), add 3 lots of (ab), which gives you 10 lots of (ab).

The key here is to just think of as a number. might be 2, might be 6, and would therefore be 12.

(7 lots of 12) + (3 lots of 12) gives you (10 lots of 12).
9. (Original post by Carrot_Cake_13)
Okay I'm fine with everything you explained up until the last sentence...

So...I understand to simplify you need to add the 7+3 which gives us the 10.
But if you add the ab + ba... Does it not give us 2 a's and 2 b's.
Yet in the answer there is only one a and one b represented - 10ab

I don't know if anything I said ^^ makes sense :/
it's 7 lots of ab plus 3 lots of ab giving you 10 lots of ab.
Edit: You have got to be kidding me.
10. (Original post by The Polymath)
We got to , which I'm assuming you're okay with.

So you start with 7 lots of (ab), add 3 lots of (ab), which gives you 10 lots of (ab).

The key here is to just think of as a number. might be 2, might be 6, and would therefore be 12.

(7 lots of 12) + (3 lots of 12) gives you (10 lots of 12).
Ohmygossh.... Hehehehe thank you

I'm feeling very erm... Stupid now
11. (Original post by Carrot_Cake_13)
Okay I'm fine with everything you explained up until the last sentence...

So...I understand to simplify you need to add the 7+3 which gives us the 10.
But if you add the ab + ba... Does it not give us 2 a's and 2 b's.
Yet in the answer there is only one a and one b represented - 10ab

I don't know if anything I said ^^ makes sense :/
Do you accept that a+a=2a?

We have 2 a's on the left and 1 on the right but this is not a problem.
12. (Original post by Carrot_Cake_13)
Ohmygossh.... Hehehehe thank you
I'm feeling very erm... Stupid now
No worries, I have to put up with far worse from Keromedic all the time

(Original post by keromedic)
x
13. (Original post by Mr M)
ab = ba because the order of multiplication does not matter*.

* Anyone who mentions matrices here deserves a punch.
Quaternions

(ducks for cover)

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