The Student Room Group

help needded

ddfdfdfd.png

Scroll to see replies

Reply 1
bumppp
Reply 2
Original post by madfish
ddfdfdfd.png


It looks like a midpoint. But only from what you posted, I think it can't be concluded.
What do they say in the exercise? (Or example, whatever it is)
Reply 3
Original post by madfish
ddfdfdfd.png


What's the original question?
Reply 4
the first picture doesnt work
Reply 5
Original post by purplemind
It looks like a midpoint. But only from what you posted, I think it can't be concluded.
What do they say in the exercise? (Or example, whatever it is)

yea, it's a mid point, but I dont see how by dividing it by 2 they get b or 2a? is it correct?
Reply 6
Original post by madfish
yea, it's a mid point, but I dont see how by dividing it by 2 they get b or 2a? is it correct?

I don't know either, if would be useful if you posted the original question. :biggrin:
Reply 7
Original post by joostan
What's the original question?

yea, it's a mid point, but I dont see how by dividing it by 2 they get b or 2a? is it correct?
Reply 8
Original post by purplemind
I don't know either, if would be useful if you posted the original question. :biggrin:

we don't need it but :P i am just checking to see if the division by 2 is correct?
Reply 9
Original post by madfish
yea, it's a mid point, but I dont see how by dividing it by 2 they get b or 2a? is it correct?


We can see its a mid point but we haven't got enough information to help you. . .
(edited 11 years ago)
Reply 10
Original post by joostan
We can see its a mid point but we haven't got enough information to help you. . .

I am just not sure about that division by 2. I didn't get b or 2a when I did it... how does it work? We dont need the question :smile:
Reply 11
Original post by madfish
I am just not sure about that division by 2. I didn't get b or 2a when I did it... how does it work? We dont need the question :smile:

The division of (2a - 4)/2 does not give 2a unless a = -2
Similarly the division of b can give the given result but only for a specific value of b
Reply 12
Original post by joostan
The division of (2a - 4)/2 does not give 2a unless a = -2
Similarly the division of b can give the given result but only for a specific value of b

okay then the solution bank is not correct...
Reply 13
Original post by madfish
okay then the solution bank is not correct...


Depends on the question. If it said given this is true find b, then yes the bank is correct.
The solution then goes on to do this and find b.
Reply 14
Original post by madfish
okay then the solution bank is not correct...


Why don't you post the original question so we can see what you're being asked to work out? It looks like they've calculated the midpoint of a line joining two points and then set this equal to some other point, which allows them to solve for b and a. However, unless you tell us what this other point is supposed to be, no-one can give you a proper answer!
Reply 15
Original post by davros
Why don't you post the original question so we can see what you're being asked to work out? It looks like they've calculated the midpoint of a line joining two points and then set this equal to some other point, which allows them to solve for b and a. However, unless you tell us what this other point is supposed to be, no-one can give you a proper answer!

The points V(−4,2a) and W(3b,−4) lie on the circle centre (b,2a) . The line VW is a diameter of the circle. Find the value of a and b.
Reply 16
Original post by madfish
The points V(−4,2a) and W(3b,−4) lie on the circle centre (b,2a) . The line VW is a diameter of the circle. Find the value of a and b.


There's the gem!
The midpoint of the diameter VW = the centre of the circle (b,2a) so you do as the solution bank says to find a and b
Original post by madfish
The points V(−4,2a) and W(3b,−4) lie on the circle centre (b,2a) . The line VW is a diameter of the circle. Find the value of a and b.

Since VW is a diameter, then the midpoint is a circle centre (V and W have the same distance from the centre - which is your midpoint too).
Reply 18
Original post by joostan
There's the gem!
The midpoint of the diameter VW = the centre of the circle (b,2a) so you do as the solution bank says to find a and b

but their division by 2 is surly not correct?:confused:
Reply 19
Original post by joostan
There's the gem!
The midpoint of the diameter VW = the centre of the circle (b,2a) so you do as the solution bank says to find a and b



Original post by purplemind
Since VW is a diameter, then the midpoint is a circle centre (V and W have the same distance from the centre - which is your midpoint too).


We got there in the end :smile:

Quick Reply

Latest