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Original poster

Algebra homework for DS1 totally stuck!

15 replies

LemonBreeland · 30/04/2015 16:48

Hope someone can help here, really struggling with one of DS1s algebra questions tonight. I will write it below

A B
4 1
5 3
6 5
7 7
The section above is drawn as a table but I can't do that on here.

Question is:
This table shows how the number of marbles child B has, b, depends on the number of marbles child A has, a. How would you write this as an equation?

OP posts:
MirandaWest · 30/04/2015 16:52

It is b=2a-7

What year is your DS in and has he been taught how to do this type of question?

eddielizzard · 30/04/2015 16:53

b = 2a - 7

i think that's it...

RoosterCogburnIsInTheJakes · 30/04/2015 16:54

b = 2a - 7

RoosterCogburnIsInTheJakes · 30/04/2015 16:54

Too slow!

MirandaWest · 30/04/2015 16:55

The way I do it is to look at the difference between the values of b. There is a difference of 2 each tune which tells me to multiply a by 2 (can't actually remember why this works but it does). Then see what you need to do to get to the actual number ie for a=4 you multiply by 2 and get 8 so then you need to subtract 7 to get to 1.
For a = 5 multiply by 2 to get 10 and then subtract 7 to get to 3 etc

grassroots · 30/04/2015 16:55

Miranda, do you have a child-friendly explanation of how to approach that type of problem? I have just made a pigs ear of trying to explain it to DS….

grassroots · 30/04/2015 16:56

Thank you!

Original poster
LemonBreeland · 30/04/2015 16:56

Thank you Miranda. He is in P7 in Scotland. He can't explain how he has done it in class, or even if he has done it in class before.

Can you explain the workings for me please?

OP posts:
Original poster
LemonBreeland · 30/04/2015 16:57

Oops cross posted

OP posts:
MirandaWest · 30/04/2015 16:58

Am just seeing how DS does at it before giving any claim to being able to explain it to children Grin

Original poster
LemonBreeland · 30/04/2015 16:59

Thanks Miranda I see that now

OP posts:
MirandaWest · 30/04/2015 17:02

I was battling with Minecraft just then but he did basically understand it. I know he's done things like that before as I help in his class sometimes so have an idea of what they do in maths.

He's in year 6 so a similar age to a child in P7 in Scotland. He is pretty good at maths so id say it is quite challenging for that age.

MirandaWest · 30/04/2015 17:02

DS was the one doing minecraft and humouring me about maths btw...

piggychops · 30/04/2015 17:05

He must be doing really well at school OP. DS is in the top set for maths in S2 and they covered this last month Smile
If he hasn't covered it, his teacher may have given it as an extension question to get him thinking about how to solve processes, which is great to see.

Original poster
LemonBreeland · 30/04/2015 17:34

My DSes school must be really pushy. He isn't even in the top maths group in his year group. I just wish he wouldn't completely close up and make it so difficult for us to help him.

OP posts:
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