Author Topic: hielly's maths thread (Read 25245 times) Tweet Share

TrueTears · « **Reply #75 on:** March 14, 2009, 09:54:37 pm »

Quote from: Hielly on March 14, 2009, 09:50:12 pm

hey THANKS GUYS ! that was a hard one for me... do you guys know if this will be in the spesh course?

from my experience i haven't met much of these questions in spesh.

alot of the geometry stuff is more 'vector-like'

Hielly · « **Reply #76 on:** March 17, 2009, 09:27:57 pm »

okay converting decimals to fractions

1. 0.07 dot on top of the 7
2. 0.26 dot on the top of 6

eg 0.07 dot on the top of 7
my method of doing it is
x=0.0777...
100x=7.7777... but i couldnt minus it ?

Flaming_Arrow · « **Reply #77 on:** March 17, 2009, 09:38:59 pm »

to convert the 0.07 to a frac
so its 2 decimal places so times by 100

$0.07 \cdot \frac{100}{100} \implies \frac{7}{100}$

to convert the 0.26 to a frac
so its 2 decimal places so times by 100

$0.26 \cdot \frac{100}{100} = \frac{26}{100} \implies \frac{13}{50}$

Hielly · « **Reply #78 on:** March 17, 2009, 09:42:56 pm »

yes but the question i asked is that there is a dot on the top of 7 meaning its recurring

Flaming_Arrow · « **Reply #79 on:** March 17, 2009, 09:45:05 pm »

Quote from: Hielly on March 17, 2009, 09:42:56 pm

yes but the question i asked is that there is a dot on the top of 7 meaning its recurring

i don't get you?

TrueTears · « **Reply #80 on:** March 17, 2009, 09:46:32 pm »

Quote from: Flaming_Arrow on March 17, 2009, 09:45:05 pm

Quote from: Hielly on March 17, 2009, 09:42:56 pm
yes but the question i asked is that there is a dot on the top of 7 meaning its recurring

i don't get you?

She means converting a recurring decimal to fractions, lol i remember this back in year 11, useless stuff not used in year 12 but good to know, i forgot how to do it LOL

EDIT: maybe i'll revise it later after i am not busy

Flaming_Arrow · « **Reply #81 on:** March 17, 2009, 09:49:04 pm »

Quote from: TrueTears on March 17, 2009, 09:46:32 pm

Quote from: Flaming_Arrow on March 17, 2009, 09:45:05 pm
Quote from: Hielly on March 17, 2009, 09:42:56 pm
yes but the question i asked is that there is a dot on the top of 7 meaning its recurring

i don't get you?
She means converting a recurring decimal to fractions, lol i remember this back in year 11, useless stuff not used in year 12 but good to know, i forgot how to do it LOL

EDIT: maybe i'll revise it later after i am not busy

i dont rememeber doing this stuff at all lol

Damo17 · « **Reply #82 on:** March 17, 2009, 09:53:00 pm »

what you do is let $x=0.0\dot{7}$

$100x=7.\dot{7}$
$100x-10x=7$ $10x$ because $x=0.0\dot{7}$ and you want to minus $0.\dot{7}$

$\therefore$ $x=\frac{7}{90}$

shinny · « **Reply #83 on:** March 17, 2009, 09:53:29 pm »

Due to latex fail (or is it just me?), I'll just word the answer.

Let 0.07 recurring be x, so 10x is 0.7 recurring and 100x is 7.7 recurring. Hence, 90x is 7, x=7/90

Next one is the same deal actually...exact same steps but just different figures. You should get x=24/90

EDIT: oh latex is back D:

Damo17 · « **Reply #84 on:** March 17, 2009, 10:15:20 pm »

second one:
$x=0.2\dot{6}$
$100x=26.6$ here you can't times x nicely to get 0.6 so you times x by 10 so you can minus 2.6.

$100x-10x=26.6-2.6$
$\therefore$ $x=\frac{24}{90} =\frac{4}{15}$

Hielly · « **Reply #85 on:** March 21, 2009, 11:10:43 pm »

thanks need help on vectors, can someone please exaplin this question i get the '-' and '+' wrong

Flaming_Arrow · « **Reply #86 on:** March 21, 2009, 11:12:38 pm »

which part do u need help with?

Hielly · « **Reply #87 on:** March 21, 2009, 11:16:26 pm »

just need an explanation on that question for b,c and hopefully i can do the rest. mainly stuck on whether is should be a minus or plus

Flaming_Arrow · « **Reply #88 on:** March 21, 2009, 11:25:29 pm »

$\vector {PB} =\vec{PO}+\vec{OB}$

we know that $\vec{AP}=\vec{2PB}$

$\vec{AO}+\vec{OP}=2(\vec{-0P}+\vec{OB}})$

$-a+ \vec{OP}=-2\vec{OP}+2b$

$\vec{OP} = \frac{1}{3}(a + 2b)$

$\vector {PB} =\frac{-1}{3}(a + 2b) +b$

$\vector {PB} = \frac{1}{3}(b-a)$

Flaming_Arrow · « **Reply #89 on:** March 21, 2009, 11:50:08 pm »

we know that OA = a, AO is in the opposite direction so its -a

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