can anyone help me work this out? 5(2s-7)+3s-9(s-7)

[ssd]

help!

is it defnitely 42fg or is it just 42f?

Factorise means put in the brackets so look for something all the terms have in common.

42, 35 and 21 are all multiples of 7 so take that out

42fg - 35f2 + 21 f3 = 7(6fg - 5f2 + 21f3)

then if you look in the bracket, each term has at least one f so take that out too.

7(6fg-5f2+21f3)= 7f(6g-5f+21f^2)

hope that is ok. Typing on iPod so will get lap top if you have any q's on that!

Aaargghh! That 21 should of course be 3!!!!! 7x3=21!

42f - 35f(squared) + 21f(cubed)

We are trying to simplify this equation, you need to see what all of the 'terms' (42f, -35f(squared) and 21f(cubed) have in common. First look at the numbers in front of the 'f'. What you need to do is find a number (a factor) of 42, 35 and 21. So find a number that has all three of those numbers in its times table.

In this example it is 7.

so take 7 out of the equation and you will get

7(6fg - 5f(squared) + 3f(cubed))

Now you see what else they all have in common. They all have 1 f in. So you can take f out as well

This will give you
7f(6g - 5f + 3f(squared))

Oh bum, we're trying to factorise, not simplify - ignore my first sentence!

maryz pmsl at us "helping" when we're really just secretly enjoying being able to do some maths!

To be pedantic, I didn't divide the 21 by 7 to give 3.

thanks so so much

[bgrin]

maryz can you recommend a book I could buy to help dd with maths homework? she is doing stuff I can't even begin to understand and I want to be able to help. she's 12, first yr in secondary school in scotland

I'd really appreciate any advice, I look up websites and can't even figure out what I'm looking for eg. bbc bitesize/understanding maths etc. I don't even know the names of things, eg. factorise, simplify, its all beyond me! also means, medium etc, ratios, significant numbers, its all a mystery to me, I'd love a book that helped me help dd

ssd - not maryz so you didn't ask me but I'll try to help anyway.

Does your DD's school subscribe to a website like MyMaths? Kids seem to like this and it has online lessons, examples as well as questions and homeworks.

Perhaps you could ask your DD's teacher for a textbook to support their course?

What about a basic maths dictionary so you knew where to look up stuff? There are only 5 main areas of maths - Algebra, Number, Data handling, Shape & Space and Measure and the things in your list are from 3 of the!!

Failing that - maths is hierarchical so any homework should be followed on from class work with good worked examples in her exercise book so she 'should' be able to tackle HW.

hope there's something to think about without recommending a specific text - sorry for butting in .... again

Yes, MyMaths is a subscription site - but lots of schools do use it or other similar ones.

kids don't seem to think they are doing maths because it is on the internet but they are encouraged to use it with a pen and paper to the side for calculations!

He should be writing down the calculations - the factorising question might be worth 3 marks at GCSE and I would have got at least 2 out of 3 even with my number mistake!

Something online should just be one aspect of learning - to support and reinforce really - but as I said there are excellent tutorials on there and it does make 3D shapes much easier

In fact I'd like to go back to school - I'm sure I would do really well now

me too!

www.mathsisfun.com/

Try the above link the explanations are brilliant, (I've even borrowed some of their pizza diagrams to help with teaching fractions)

{blush] you might have to copy and paste it....

Thank you

Don't do the rotation game - it is v. addictive even more addictive than mumsnet