You are Here: Home >< Maths

# Could someone explain this Expression? Watch

Announcements
1. Hi,

This is an example question and its solution. However, I don't understand a couple of things in it. Could somebody explain?

So, why does the '-6' disappear in stage 2? And, why does a minus sign appear in front of the 3?

Thanks!
2. In stage 2 you are adding like term 3 - 6 =-3
3. (Original post by Exceptional)
Hi,

This is an example question and its solution. However, I don't understand a couple of things in it. Could somebody explain?

So, why does the '-6' disappear in stage 2? And, why does a minus sign appear in front of the 3?

Thanks!
(Original post by Exceptional)
Hi,

This is an example question and its solution. However, I don't understand a couple of things in it. Could somebody explain?

So, why does the '-6' disappear in stage 2? And, why does a minus sign appear in front of the 3?

Thanks!
4. (Original post by EnterNamehereplz)
Ah, that makes sense! Thanks guys.
5. (Original post by EnterNamehereplz)
Using the same technique, is this correct?

6. (Original post by Exceptional)
Using the same technique, is this correct?
Well your second line is fine, and although the fourth line follows from the third line, the third line itself has some serious errors.

From:

We can remove the second bracket to get

Then the 2 and -2 will cancel, giving.

Can you finish from there?

You correctly handled the signs from inside the brackets, but the 40 and 288 were incorrect.
7. (Original post by ghostwalker)
Well your second line is fine, and although the fourth line follows from the third line, the third line itself has some serious errors.

From:

We can remove the second bracket to get

Then the 2 and -2 will cancel, giving.

Can you finish from there?

You correctly handled the signs from inside the brackets, but the 40 and 288 were incorrect.

Why do we take away the brackets from '-2'? Why not from (20-12^2)?

Would it just be 20-144? So -124?

Or are the brackets expanded? So -20 + 144? So 124?
8. (Original post by Exceptional)
Hi,

This is an example question and its solution. However, I don't understand a couple of things in it. Could somebody explain?

So, why does the '-6' disappear in stage 2? And, why does a minus sign appear in front of the 3?

Thanks!
Just gonna point out the fact that it should be a negative on the last line.
9. (Original post by RDKGames)
Just gonna point out the fact that it should be a negative on the last line.
Thanks!
10. (Original post by Exceptional)

Why do we take away the brackets from '-2'?
Because by convention, you are adding a negative number which is represented by +(-2) however this would also be the same as subtracting 2 so we ignore the brackets which would be represented by -2.

Why not from (20-12^2)?
Technically, you could indeed remove the brackets in the expression however you are treating the inside bracket as 2 separated terms therefore you would distribute the -1 accordingly, leaving you with .

Would it just be 20-144? So -124?
20-144 is indeed -124. Now when you consider -(20-144) you get -(-124) which turns into +124 within your equation.

Or are the brackets expanded? So -20 + 144? So 124?
Essentially, yes.

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: October 11, 2016
Today on TSR

### What if I get all As and one U?

Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams

## Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.