Question

(28 - 7b)/ (b -4) * (1/ ( b + 10)

Answer 1

Are you able to factorise 28-7b [which is the numerator of the first term]?

Answer 2

yes

Answer 3

What did you get when you factorised it?

Answer 4

i don't know how to factorize the problem i kind of tried and got confused what did you get

Answer 5

Come on eb you got this!

Answer 6

You told me that you knew how to factorise: 28-7b. I want to see what you got for just doing that?

Answer 7

\[\frac{ 27-7b}{ b ^{2-}40 }\]

Answer 8

You're getting all the knowledge that you've learnt mixed up. You're confusing yourself even more, when I asked you to factorise 28-7b. Could you do that step for me please?

Answer 9

i forgot how to do that i thought you was talking about subtracting them

Answer 10

If you factorise, you take a common factor for each of the terms. For EXAMPLE: Factorise 4+8x.
The factor for the two terms is 4. So we take the 4 out and we get:
\[4(1+2x)\]
WHen you distibute or expand, you would get the same two terms as before.

Answer 11

One more note- If you take out the common factor, you have would be changing the terms inside the brackets. If you factorise 4+8x and take out 4, you don't go like this:
\[4(4+8x)\]
That would give you a completely different result. You must account for the factor taken out and you must make it possible to fit everything together.
What would be the factor for 28-7b then?

Answer 12

you would be*

Answer 13

7(4-1b)

Answer 14

Well done. you don't need the 1 because 1b=b. It's the same thing. Okay if we also factorise the minus sign out, what would we get then?

Answer 15

So for EXAMPLE, if we take out the minus sign in this example: 4(1-2x)=-4(2x-1), that would be the end result.

Answer 16

okay

Answer 17

Could you show me what you get now when you take out the minus from: 7(4-b)?

Answer 18

7(4b)

Answer 19

Did you read my example properly?

Answer 20

Factorise the minus also means take the minus out.

Answer 21

I don't mean literally take it out. I mean factorise the minus sign out.

Answer 22

Don't you see that if you do that, it wouldn't make sense mathematically if you literally took the minus sign out?

Answer 23

-7(b-4)

Answer 24

@eb3001 YES! Now you have this:
\[\frac{-7(b-4)}{b -4} \times \frac{1}{b + 10}\]

Answer 25

Now you can cancel the b-4 with the denominator and numerator.

Answer 26

@eb3001 Come on you're almost done! Just follow along with @Azteck

Answer 27

alright \[-7*\frac{ 1 }{ b+10 }\] so you get this

Answer 28

\[-7* \frac{ -7 }{ 7b+70 }\]

Answer 29

\[\frac{ 7b }{ 7b+70}\]

Answer 30

Oops, you can't multiply the whole thing by -7, just the numerator.
If it was -7/-7 then in that cause you could.

Answer 31

\[\frac{ -7b }{ b+10 }\]

Answer 32

Where did that b come from?

Answer 33

Um you were correct when you came to this stage:
\[-7\times \frac{1}{b+10}\]

Answer 34

The last step would just be putting the -7 on top of 1/b+10

Answer 35

my bad \[\frac{ -7 }{ b+10 }\]

Answer 36

Yep. Correct! Good job.

Answer 37

Ha, there you go eb :)

Answer 38

thanks

Answer 39

No worries.