Year 12s: what will be the first way you research your future options? >>

Maths on Gonna die!!!!!

Can anyone help me o this equation. Ho do I do it??

x+2y=9
y=x+3
help!!!! I can't do simultaneous equations at all

Scroll to see replies

At just a cursory glance, x = 1, y = 4?

Edit: Why am I getting negged? Geez, you help someone, honestly, and you get negged for it. The answer was obvious to me, if the OP understands and masters the method she'll be able to do it deductively in her mind too.

(edited 11 years ago)

Reply 2

madfish

Original post by fazza

Can anyone help me o this equation. Ho do I do it??

x+2y=9
y=x+3
help!!!! I can't do simultaneous equations at all

sub y=x+3 in the first equation and solve

x+2(x+3)=9
x+2x+6=9
3x=3
x=1

y=1+3=4

x=1 y=4

job done

why was a negged for this you abhorrent people?

(edited 11 years ago)

Reply 3

SpiggyTopes

Original post by fazza

Can anyone help me o this equation. Ho do I do it??

x+2y=9
y=x+3
help!!!! I can't do simultaneous equations at all

Get both equations in terms of y...

i.e.
x+2y=9

2y=9-x

y= 4.5 -0.5x

Since the other equation is y=x+3,

x+3=4.5-0.5x

Can you do the rest?

Reply 4

squeakysquirrel

Original post by fazza

Can anyone help me o this equation. Ho do I do it??

x+2y=9
y=x+3
help!!!! I can't do simultaneous equations at all

If you isolate x therefore x = 9 - 2y

do the same with the second equation therefore you will have two values from the two equations for x - then try

Reply 5

fazza

Thanks so much I reckon I ca do suns like these now thanks. Xoxo

Reply 6

R4INBOW

how i miss gcse maths.

Reply 7

madfish

Original post by R4INBOW

how i miss gcse maths.

this would have been one of the more difficult questions :redface:

dawwww

Reply 8

CJKay

Original post by R4INBOW

how i miss gcse maths.

I know, right?

Reply 9

davros

Original post by madfish

this would have been one of the more difficult questions :redface:

dawwww

don't you mean one of the easier questions?

Reply 10

Robbie242

Original post by davros

don't you mean one of the easier questions?

Agreed, I'd say vectors would be one of the hardest questions on a gcse maths paper at times

Reply 11

madfish

Original post by davros

don't you mean one of the easier questions?

would it of been? bleh i cant even remember now :L

Reply 12

madfish

Original post by Robbie242

Agreed, I'd say vectors would be one of the hardest questions on a gcse maths paper at times

they weren't on my gcse on spec

Reply 13

Season One

Original post by R4INBOW

how i miss gcse maths.

Those were the days :wink:

Reply 14

madfish

Original post by Robbie242

Agreed, I'd say vectors would be one of the hardest questions on a gcse maths paper at times

for me, at gcse level the hardest thing was probability and transformations

Reply 15

davros

Original post by madfish

would it of been? bleh i cant even remember now :L

Well there are questions that make you think, and questions that just require you to follow a process.

Yes, you have to learn the process and practise it, but when you've done that you can repeat it almost without thinking - this is one of those questions.

Reply 16

Robbie242

Original post by madfish

for me, at gcse level the hardest thing was probability and transformations

Probability at gcse is much easier than S1, with probability you dealt mostly with mutually exclusive events, at alevel you have conditional probability etc. And yes transformations, I didn't even find them out until C1 and they appeared on my gcse paper whilst I stared blankly at them