# Very hard Maths Vector question - EDIT: not so hard after all

Can you work out the vector OG, if so how?

(i have the answer, but i don't know how to work it out)

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C to E is -2c + 3d

C to G is a quarter of the size =

-1/2c + 3/4d

= 3/2c + 3/4d
i have problems on these type of questions too.. the ones where they give you a couple of vectors, then give you the point on a line that hasnt got a vector and ask you to find a vector
THANKS A MILLION

and dam, why didnt i think of that

u got the answer correct, however in the exam they will usually tell u to compare 2 vectors, so its better if u factorise which is why the answer in the marking scheme is (3/4)(d+2c) - three quarters of (d+2c)
mm nice red devil i think i get it now im gonna go try a couple
Ok.

CE = -2c + 3d
CE = 3d - 2c

CG = 0.25(3d-2c)

Therefore...

OG = 2c + 0.25(3d-2c)
OG = 2c + 0.75d - 0.5c

so...

OG = 1.5c + 0.75c

Right or wrong?
I think I might have went wrong somewhere...
correct hbk

but your vactors are multiplied by decimals instead of reddevils fractions and the mark schemes factorisation
Wicked. I wasn't really confident with vectors but after doing that on paper just now, I think I've finally got the concept of it.

Yeah obviously it'd be in fractions. Just didn't want to confuse anyone if it was right using '/' a lot.
Yeah vectors were a real nightmare for me, just didn't get them, sat down with a few vector q's and after constant practice, piece of cake!

Just practice them and you'll be fine
EC = -3d + 2c
DC = -d + 2c

OF = d + -1/2 d + c (half of DC)
= 1/2d + c

OG = 3d + 3/4EC
= 3d -3/4d + 1/4c
= 2.25d + 0.25c

i think this is right
salawat... DC does not equal -d+2c

and IRAQIS RULE!!!

EDIT: sorry, it does - but your mistake is here i think:

OG = 3d + 3/4EC
= 3d -3/4d + 1/4c
= 2.25d + 0.25c

you assumed that 3/4EC = -(3/4)d+(1/4)c , actually its 3/4(3d)+3/4(2c)
Didn't realise there were any iraqis on here before lol
to the OP...can i say thank you for this post...

you, thanks to this post, reassured me of my vector ability

and p.s. Hbk, nice way of working it out...and im suprised the question gave you what CG was...normally they dont!
motiv3
to the OP...can i say thank you for this post...

you, thanks to this post, reassured me of my vector ability

and p.s. Hbk, nice way of working it out...and im suprised the question gave you what CG was...normally they dont!

I don't think you could do it without knowing what CG was in relation to CE. Aslong as they don't state the magnitude of the vector, it still needs working out.

I agree with you though, nice refresher question
ye, in these sort of questions, u always need to figure out what the unknown vector is...i never got that before until i did some past papers...these kinda things teachers dont well teach...they say it will be there..
vector ce = vector co + vector oe
ce = -2c + 3d

vector og = vector oc + vector cg (Note cg= 1/4 of ce)
= 2c -2c+3d/4

(taking lcm) = 8c-2c+3d/4
= 6c+3d/4

VECTOR OG = 6c+3d/4

I think i am right if anyone think i am wrong please point out my mistake
it is right however you used its just expressed in a different way

(6c+3d)/4 = (3/4)(d+2c)
I got 3/4d + 3/2c