Help needed - Simplifying

I have been set a question and I'm completely stuck. I have the answer but no idea about how to get there. I'm a distance learner and my tutor is on holiday until August and I have a massive bee in my bonnet at the moment so any help would be greatly appreciated.

Question: simplify
5-√75
-2

I've got as far as:
5-(5√3)
-2

But apparently the answer is:
5(1-√3)
-2

How do I get to the answer?! Is it even possible? It wouldn't be the first time ICS have made a mistake but this seems like it would be a big mistake that someone would have picked up on so I get the feeling I'm just being really dim. Can someone PLEASE enlighten me? :confused:

(edited 10 years ago)

Reply 1

kara1

11

I know this is working back from the answer but.. Multiply out the bracket on the top of the fraction in the answer and see what you get

Original post by RachaelBee

I have been set a question and I'm completely stuck. I have the answer but no idea about how to get there. I'm a distance learner and my tutor is on holiday until August and I have a massive bee in my bonnet at the moment so any help would be greatly appreciated.

Question: simplify
5-√75
-2

I've got as far as:
5-(5√3)
-2

But apparently the answer is:
5(1-√3)
-2

How do I get to the answer?! Is it even possible? It wouldn't be the first time ICS have made a mistake but this seems like it would be a big mistake that someone would have picked up on so I get the feeling I'm just being really dim. Can someone PLEASE enlighten me? :confused:

There's no mistake. The answers are equivalent.

You should know

ab + ac = a(b+c)

Reply 3

HexBugMaster

1

No it's not a mistake, you can take out 5 as the common factor from 5-(5√3) and thus get 5(1-√3)

Reply 4

SaySaam

Original post by RachaelBee

I have been set a question and I'm completely stuck. I have the answer but no idea about how to get there. I'm a distance learner and my tutor is on holiday until August and I have a massive bee in my bonnet at the moment so any help would be greatly appreciated.

Question: simplify
5-√75
-2

I've got as far as:
5-(5√3)
-2

But apparently the answer is:
5(1-√3)
-2

How do I get to the answer?! Is it even possible? It wouldn't be the first time ICS have made a mistake but this seems like it would be a big mistake that someone would have picked up on so I get the feeling I'm just being really dim. Can someone PLEASE enlighten me? :confused:

Both 5 and 5√3 have a multiple of 5 in them. 5=5x1 and 5√3=5x√3

You can factorise 5- 5√3 by taking a multiple of 5 out. You're multiplying everything inside the bracket by what's outside the bracket, in this case the 5.

Does that make it a little clearer?

Posted from TSR Mobile

Reply 5

RachaelBee

OP

20

Thanks but I still don't get where the - goes? I'm feeling so stupid at the moment but my course material doesn't explain it and I haven't studied math in the last 6 years.

Reply 6

HexBugMaster

1

Original post by RachaelBee

Thanks but I still don't get where the - goes? I'm feeling so stupid at the moment but my course material doesn't explain it and I haven't studied math in the last 6 years.

5-5x(sq. rt. 3) = 5(1-1x(sq. rt. 3)

And don't worry, maths gets extremely tricky if you don't practise it for a while. If I miss my maths practice for a day I forget concepts I haven't worked on for enough, let alone not doing it for 6 years :biggrin:

(edited 10 years ago)

Original post by RachaelBee

Thanks but I still don't get where the - goes? I'm feeling so stupid at the moment but my course material doesn't explain it and I haven't studied math in the last 6 years.

Do you understand the following?

5 - 5x = 5(1-x)

This is exactly the same with

x=\sqrt 3

Factorising expressions like this is a grade D skill at GCSE so you may need to spend some time studying the algebra section of a GCSE revision guide.

Reply 8

HexBugMaster

1

How does it happen that no one posts for a period of time and then everybody posts at the same time :biggrin:

Reply 9

iCiaran

11

Original post by HexBugMaster

How does it happen that no one posts for a period of time and then everybody posts at the same time :biggrin:

One person finds it, post bumps it back up to the sidebar and loads more people find it :tongue:

Reply 10

HexBugMaster

1

Original post by iCiaran

One person finds it, post bumps it back up to the sidebar and loads more people find it :tongue:

You cracked the mystery :holmes:

Reply 11

m4ths/maths247

7

Original post by RachaelBee

Thanks but I still don't get where the - goes? I'm feeling so stupid at the moment but my course material doesn't explain it and I haven't studied math in the last 6 years.

Hi
I know it's not much help at this stage but hopefully it may help others in the future. :smile:

I can't help thinking £470 for the ICS distance learning course is a lot of money given (i) The materials aren't great (ii) The support is often slow and (iii) The exams are not paid for.

If you hop on amazon a secondhand Bostock and Chandler Core Maths book for less than a tenner and help here should provide a god background for pure maths.

Good luck

Reply 12

RachaelBee

OP

20

I get it!! Halle-freaking-lujah! Thank you so much everyone. :smile:

Help needed - Simplifying

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