Question

Simplify.

6a - {b - [3a - (2b + c) + 4a - (a + 2b - c)]}.
12a - 5b
6a - b + 2c
12a - 5b + 2c
b

Answer 1

First remove the brackets, working from the inside to the outside. Can you do that?

Answer 2

ill try one sec

Answer 3

um with alittle help yes

Answer 4

What is the result when you remove the brackets from -(2b + c)

Answer 5

ok i guess this is harder then i thought

Answer 6

-(2b + c) is mathematical shorthand for( -1 * 2b) + (-1 * b)
What do you get when you multiply -1 and 2b ?

Answer 7

-2b

Answer 8

Correct. Now multiply -1 and b.

Answer 9

-b

Answer 10

Right !. So -(2b + c) = -2b - c
Now remove the brackets from -(a +2b - c) by multiplying each term by the -1 that is assumed outside the leading bracket.

Answer 11

ok

Answer 12

-a-2b+c

Answer 13

Absolutely right. So now we have inside the square brackets:
[3a - 2b - c + 4a - a - 2b + c]
Can you now collect the like terms and simplify inside the square brackets.

Answer 14

ya

Answer 15

What do you get when you add 3a + 4a - a

Answer 16

6a

Answer 17

Right. So now we have inside the square brackets [6a - 2b - 2b - c + c]
So what are you left with when you add the terms in b and the terms in c inside the square brackets?

Answer 18

b cansals right

Answer 19

Yes. b disappears from inside the square brackets.

Answer 20

ok

Answer 21

6a-2c

Answer 22

Sorry. I should have said that c cancels. + c - c = 0
-2b -2b = -4b
So inside the curly brackets we have:
{b - [6a - 4b]} = {b - 6a + 4b}
Do you follow so far?

Answer 23

yup

Answer 24

We're nearly there!
So putting all the terms that are left together we have:
6a - {b - 6a + 4b} = ? when you multiply everything inside the curly brackets by -1 to enable the curly brackets to be removed.
Can you do this?

Answer 25

-b+6a-4b

Answer 26

Right again. You're getting good at this! So finally we have:
6a - b + 6a -4b = ?
You add the terms in a and add the terms in b (observing their signs) and you should have the correct answer.

Answer 27

12a-5b

Answer 28

Well done :) That is one of the choices.

Answer 29

ok thanks

Answer 30

You're welcome :)