Lowyat.NET: Latest topics by SkyShuT_T3r

Stats n Probability

~~SkyShuT_T3r~~ — Sat, 04 May 2013 22:22:10 +0800

QUOTE

Suppose X has the probability density function f(x)=kx^2 for 0<x<1 and 0 elsewhere. Explain why it is necessary that k=3 in the density function.

The question is about CDF and PDF. I have omitted parts of the question.

I noticed that if k=3, then it cancels out the 1/3 when the PDF is integrated to get the CDF. but i don't really know what to explain. Requesting insight.

[WTB] Looking for used iPad3/4

~~SkyShuT_T3r~~ — Tue, 19 Mar 2013 21:57:42 +0800

Item(s):Ipad 3 or 4 , used unit, with cellular, any storage but prefer 32GB, used MINI also can

Package includes:Everything with box

Price:Please PM me and offer me best

Warranty:Best if still have

Dealing method:COD

Location of seller:Seberang Jaya/Butterworth, Penang

Contact method/details:PM

Age of item:Please tell me

---

Item(s) conditions:You show me photos please if possible
Picture:-

Reason for sale:-

Cross and dot product

~~SkyShuT_T3r~~ — Thu, 26 May 2011 18:35:11 +0800

QUOTE

Show that lla x bll^2 = llall^2 * llbll^2 - (a . b)^2

Do i do this by expanding everything?

By expanding the LHS, i got (a2b3)^2 - 2a2b3a3b2 + (a2b3)^2 + (a3b1)^2 - 2a3b1a1b3 + (a1b3)^2 + (a1b2)^2 - 2a1b2a2b1 + (a2b1)^2

And by expanding the RHS, in the end after some cancellation, i got (a2b3)^2 + (a2b3)^2 + (a3b1)^2 + (a1b3)^2 + (a1b2)^2 + (a2b1)^2, then im stucked. Did i make a mistake somewhere?

EDIT: i found out how liao. /close

exponential decay

~~SkyShuT_T3r~~ — Sat, 21 May 2011 14:12:16 +0800

Yea, it's me again seeking for help in maths if u do rmb me.

QUOTE

Strontium-90 is produced at a rate of 3kg/yr. How much the strontium produced since 1971 was still around in 1992? Half life of strontium is 28 years.

i need to integrate the decay function from 0 to 21, then subtract the answer from the total strontium produced, right? but i dont know how to write out the decay function. need help.

Can u spot the LOL?

~~SkyShuT_T3r~~ — Fri, 13 May 2011 20:44:25 +0800

http://www.abssystems.com.my/index.php?action=home

Can u spot it? or not?

Linear transformation

~~SkyShuT_T3r~~ — Tue, 10 May 2011 00:42:07 +0800

T(x1 , x2) = (4x1 - 2x2 , 3lx2l)

Show that the transformation T is not linear.

i do know if

T(x1 + x2) =/= T(x1) + T(x2)

or

cT(x1) =/= T(cx2)

or

T(0) =/= 0

then the transformation is not linear. but how do i do it? hints please.

WTA vectors

~~SkyShuT_T3r~~ — Mon, 25 Apr 2011 19:32:21 +0800

Find a vector of length 1 which is perpendicular to both u and v. Do not use cross product. u = (-3, 1, 2). v = (4, 0, -8)

How do start with the question? My lecturer haven't discuss cross product with us yet so I think that's why he specified to not use cross product.

So, I tried using dot product to find the equation of plane by letting n = (a, b, c) but I currently have no idea of how to find the variables. Have I missed out something? Or am I using the wrong method?

WTA vectors

~~SkyShuT_T3r~~ — Mon, 25 Apr 2011 13:35:41 +0800

WTA about maths

~~SkyShuT_T3r~~ — Wed, 13 Apr 2011 21:35:44 +0800

So here's the question:

The cost of fuel to propel a boat through the water (in dollars per hour) is proportional to the cube of the speed. A certain ferry boat uses $100 worth of fuel per hour when cruising at 10 miles per hour. Apart from the fuel, the cost of running this ferry (labour, maintenance, and so on) is $675 per hour. At what speed should it travel so as to minimise the cost per mile traveled?

The graph should be somewhat like this i think,

but problem is I can only find the equation for the red line from the information given, how can I find the equation for the curve? In need to be enlightened.

To all /k/tards

~~SkyShuT_T3r~~ — Fri, 25 Mar 2011 22:38:26 +0800

i recommend u all to watch a korean drama - Dream High

[YOUTUBE]Dh8t8tdwAiA[/YOUTUBE]

i was direction-less for the past year and has been studying blindly without a clear goal. the drama showed me what a dream is like. taught me to have desire and passion for my dream and the never give up spirit. and now i have a clear goal of my life. it's really a motivating drama. highly recommended for those who feel like something is missing in their life.

» Click to show Spoiler - click again to hide... «

kthxbai.

WTA about maths

~~SkyShuT_T3r~~ — Tue, 22 Mar 2011 23:09:22 +0800

Let f(x) = 3 sin x - 2 cos x. Show that f can b written as a sine function which has been shifted horizontally, then stretched vertically.

i think i shld derive f(x) into something like A sin (x + B), right? using newton's iterative formula, i got B = 0.588. and the max. point for a sine graph is at x =1.571rad. so, by substituting 2.159 (1.571 + 0.588) into f(x) i get the amplitude, A = 3.606. so, f(x) = 3.606 sin (x - 0.588). i tried plotting both the graphs using a software and yeah, both are the same.

so my question is, how to derive from f(x) = 3 sin x - 2 cos x to f(x) = 3.606 sin (x - 0.588)?

Maths freaks and geniuses please come..

~~SkyShuT_T3r~~ — Sat, 19 Mar 2011 20:51:01 +0800

... which i totally cannot brain.

» Click to show Spoiler - click again to hide... «

any hints will do. and pls do let this thread b troll-free.

inb4 education essentials ------->. ald posted thr still no good replies atm. so i trying my luck at /k/. where all the geniuses are.

WTA about maths

~~SkyShuT_T3r~~ — Sat, 19 Mar 2011 20:34:38 +0800

Here's the question:

Let f : R2 --> R be the function where the output is the angle, in radians, from the positive x-axis to the line connecting the origin with the input. Explain why f is not a function. Define f more carefully so that is a function.

the 1st half of the question says that f is not a function but the 2nd half says it is a function. so, im not quite sure though what the question is asking.

WolfTeam

~~SkyShuT_T3r~~ — Sat, 29 Jan 2011 14:39:45 +0800

i found some old threads for lyn wolfteam players but it was closed due to unknown reasons. i would like to start a new wolfteam thread but before that. who plays wolfteam regularly here? And for those who dont know what's wolf team.

It's a game from softnyx. Here's the homepage.

It's a little different from any typical online FPS because when u press 3 u transform into wolves instead of using a knife. And there are certain game modes where players fight wolves with wolves or fight wolves with humans and vice versa. So, there's something new for typical fps players. They have whole lot of guns to be bought including grenade launchers, rocket launchers, turrets and even flamethrowers. The downside is that their cash users overpowered non-cash users. Here's a video of the gameplay.

[YOUTUBE]RkzBdu2IE3c[/YOUTUBE]

I started playing it few years back and u may call me a veteran if u wan.

» Click to show Spoiler - click again to hide... «

LYN WolfTeam players (Forum nick - Callsign)
1. ~~SkyShuT_T3r~~ - Dare2Love

WolfTeam

~~SkyShuT_T3r~~ — Sat, 29 Jan 2011 14:01:05 +0800

It's a game from softnyx. Here's the homepage.

It's a little different from any typical online FPS because when u press 3 u transform into wolves instead of using a knife. And there are certain game modes where players fight wolves with wolves or fight wolves with humans and vice versa. Here's a video of the gameplay.

[YOUTUBE]RkzBdu2IE3c[/YOUTUBE]

The thing that is special about this game is that they have some sort of filtering before u can join or start a game. For example, in a room, if ur ping is not compatible with other players, u get kick out of the room automatically. They have whole lot of guns to be bought including grenade launchers, rocket launchers, turrets and even flamethrowers. The downside is that their cash users overpowered non-cash users.

I started playing it few years back and u may call me a veteran if u wan.

» Click to show Spoiler - click again to hide... «

I am just wondering if any1 else play this game. Or it's just me.

i have a problem on my iTouch 2nd gen

~~SkyShuT_T3r~~ — Thu, 27 Jan 2011 17:06:01 +0800

Occasionally. when im playing some games on my ipod. it just crashes and go back to home screen. now the frequency has increased and even safari and the facebook app crashes now.

p/s: my ipod is jailbrokened

Lowyat.NET: Latest topics by ~~SkyShuT_T3r~~

Stats n Probability

[WTB] Looking for used iPad3/4

Cross and dot product

exponential decay

Can u spot the LOL?

Linear transformation

WTA vectors

WTA vectors

WTA about maths

To all /k/tards

WTA about maths

Maths freaks and geniuses please come..

WTA about maths

WolfTeam

WolfTeam

i have a problem on my iTouch 2nd gen

Lowyat.NET: Latest topics by SkyShuT_T3r