Post by: hello_kitty on February 14, 2011, 07:24:54 pm
Show all working.
What does 5 units mean?
I did...
m = y2 - y1/x2 - x1
5 = -1 - y/8-5
5 = -1 - y/3
15 = -1 -y
16 = -y
I have no idea why i put 5 as m
y = -16
Thnaks!
AND ALSo..
just clarifying...
for a question like:
y -3 = 3/2 (x - 6)
would you expand the bracket first? then multiply the two to the LHS? OR multiply the 2 to the left hand side so it is
2(y - 3) = 3(x-6)?
I tried both ways and got differenet answers :/
could i see both ways workings?
thanks a lot!
Post by: JinXi on February 14, 2011, 07:28:23 pm
the distance is 5 units, not the gradient.
Try using the Pythagoreas Theorem.
You should get y= -5, y=3
Post by: Greatness on February 14, 2011, 07:29:14 pm
distance=square root ((x1-x2)^2 + (y1-y2)^2)
There may be an easier way to do this. Not quite sure, that was the first method that i thought of.
Post by: simonhu81292 on February 14, 2011, 07:31:30 pm
you are using the wrong formula as well
they are asking for the distance...
hence .. you should now use this formula
Root[(x2-x1)^2+(y2-y1)^2] ..
now you can try and solve it ...
Post by: simonhu81292 on February 14, 2011, 07:34:12 pm
both approach will still work
however ...using your first methods would be faster
y -3 = 3/2 (x - 6)
you would expand the RHS, then move the 3 to the RHS by +3
Post by: hello_kitty on February 14, 2011, 08:21:46 pm
5 = square root (8-5)^2 + (-1-y)^2
:/
Post by: ttn on February 14, 2011, 08:35:02 pm
Post by: simonhu81292 on February 14, 2011, 08:38:16 pm
then square both sides ..
you would get 25=9+(-y-1)^2
then you move the 9 on to the LHS
16=(-y-1)^2
expand (-y-1)^2
16=y^2+2y+1
bring the 16 onto the RHS
y^2+2y-15=0
solve for y
and then you will get y= -5 or 3 as your answer
Post by: ttn on February 14, 2011, 09:11:21 pm
Post by: hello_kitty on February 14, 2011, 09:19:10 pm
Post by: simonhu81292 on February 14, 2011, 10:11:28 pm
Or instead of expanding, you can just square root both sideslol...didn't think of it that way ..yeah ~~(plus/minus 4)
faster~ :D
so the answer can be either 3 or -5??yep ..that's right ;)=hello_kitty link=topic=38126.msg403523#msg403523 date=1297678750]
so the answer can be either 3 or -5??
[/quote]
yep ..that's right
Post by: luffy on February 14, 2011, 10:14:52 pm
Do you actually understand how to do the question?
If not, members of this thread have already told you how to do the question, the only way in which you will understand it properly, is if there is a teacher or someone showing you how to do it face to face, with visual representations.
Tell me if I am wrong because teaching you how to do this question (without you understanding), will not actually teach you how to do these 'type' of questions, if you get what I mean.
Post by: hello_kitty on February 14, 2011, 11:22:33 pm
25 = 10 +y^2 +2y
15 = y^2 + 2y
y^2 + 2y - 15 = 0
(y + 5) y - 3) = 0
therefore, y = -5 or y = 3.
yeah.. i get it
Post by: luffy on February 15, 2011, 05:54:14 pm
i do get it..
25 = 10 +y^2 +2y
15 = y^2 + 2y
y^2 + 2y - 15 = 0
(y + 5) y - 3) = 0
therefore, y = -5 or y = 3.
yeah.. i get it
Haha ok. My bad then.
Post by: hello_kitty on February 15, 2011, 07:35:10 pm
I just forgot what the method was for..
y2 + 2y - 15 = 0 to (y +5) (y-3) = 0
:/
Post by: brightsky on February 15, 2011, 07:38:41 pm
5 - 3 = 2