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On May 20 2010 09:59 Djzapz wrote:
Since this is solved, I have a fun one (it was for me!)
A truck is on the highway at a constant speed of "s" km/h. The truck's gas consumption is shown by:
q(s)= 1/250*((50/v)+v) in litres/km.
The driver is paid $35/hour.
Find at which speed the cost is at the minimum for the employer for a 254 kilometers drive provided that gasoline costs $1,059 per litre.
It had me confused for a while but it was cewl =D
PS: I'm horrible at math so it took me longer than it should have.
that problem is horrible... have you ever thought about the driver's family? or about his rights as a worker?
How many hours in a row you want your drivier driving?, have any fkn mba any idea on safety?
This is no math, sir, this is pure explotation.
edit:
On May 20 2010 10:37 dangots0ul wrote:Show nested quote +On May 20 2010 10:08 coltrane wrote:On May 20 2010 09:58 dangots0ul wrote:
don't worry bro, you won't be using 99% of this stuff ever after school. unless u go into math Sorry for the double post, but whoever listen this douchebag is a douchebag aswell. And even if he is right, that 1% totally owns. great logic douchebag.
 603 shitty oneliners, nothing else to add...
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On May 20 2010 10:25 Sadistx wrote:Show nested quote +On May 20 2010 09:59 Djzapz wrote:
Since this is solved, I have a fun one (it was for me!)
A truck is on the highway at a constant speed of "s" km/h. The truck's gas consumption is shown by:
q(s)= 1/250*((50/v)+v) in litres/km.
The driver is paid $35/hour.
Find at which speed the cost is at the minimum for the employer for a 254 kilometers drive provided that gasoline costs $1,059 per litre.
It had me confused for a while but it was cewl =D
PS: I'm horrible at math so it took me longer than it should have. Take the derivative and find the minimum of the function?
Yeah but you have to find the actual function which is the fun part =D
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On May 20 2010 09:47 Navi wrote:
when i saw "math" in the title i thought this would be some dissertation level shit.... so many math dudes on here
Two things...
1. He did say "terribad" in the title. 
2. I've never seen anything close to dissertation level here.
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On May 20 2010 10:37 coltrane wrote:Show nested quote +On May 20 2010 09:59 Djzapz wrote:
Since this is solved, I have a fun one (it was for me!)
A truck is on the highway at a constant speed of "s" km/h. The truck's gas consumption is shown by:
q(s)= 1/250*((50/v)+v) in litres/km.
The driver is paid $35/hour.
Find at which speed the cost is at the minimum for the employer for a 254 kilometers drive provided that gasoline costs $1,059 per litre.
It had me confused for a while but it was cewl =D
PS: I'm horrible at math so it took me longer than it should have. that problem is horrible... have you ever thought about the driver's family? or about his rights as a worker? How many hours in a row you want your drivier driving?, have any fkn mba any idea on safety? This is no math, sir, this is pure explotation. edit: Show nested quote +On May 20 2010 10:37 dangots0ul wrote:On May 20 2010 10:08 coltrane wrote:On May 20 2010 09:58 dangots0ul wrote:
don't worry bro, you won't be using 99% of this stuff ever after school. unless u go into math Sorry for the double post, but whoever listen this douchebag is a douchebag aswell. And even if he is right, that 1% totally owns. great logic douchebag. 603 shitty oneliners, nothing else to add...
clearly some one doesn't know how to go through post history. Its ok, logical reasoning is not for everyone. Someone has got to be the kid sitting in the back with the helmets and seat belts
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This kept me up a bit last night. If a and b are positive integers, prove that sqrt(a) + sqrt(b) is rational if and only if a and b are perfect squares
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On May 20 2010 12:52 dangots0ul wrote:Show nested quote +On May 20 2010 10:37 coltrane wrote:On May 20 2010 09:59 Djzapz wrote:
Since this is solved, I have a fun one (it was for me!)
A truck is on the highway at a constant speed of "s" km/h. The truck's gas consumption is shown by:
q(s)= 1/250*((50/v)+v) in litres/km.
The driver is paid $35/hour.
Find at which speed the cost is at the minimum for the employer for a 254 kilometers drive provided that gasoline costs $1,059 per litre.
It had me confused for a while but it was cewl =D
PS: I'm horrible at math so it took me longer than it should have. that problem is horrible... have you ever thought about the driver's family? or about his rights as a worker? How many hours in a row you want your drivier driving?, have any fkn mba any idea on safety? This is no math, sir, this is pure explotation. edit: On May 20 2010 10:37 dangots0ul wrote:On May 20 2010 10:08 coltrane wrote:On May 20 2010 09:58 dangots0ul wrote:
don't worry bro, you won't be using 99% of this stuff ever after school. unless u go into math Sorry for the double post, but whoever listen this douchebag is a douchebag aswell. And even if he is right, that 1% totally owns. great logic douchebag. 603 shitty oneliners, nothing else to add... clearly some one doesn't know how to go through post history. Its ok, logical reasoning is not for everyone. Someone has got to be the kid sitting in the back with the helmets and seat belts
because when I click profile in the upper right corner of your post, and then click the number of posts I dont find 600 one liners about bleach manga...
Please stay, you are so usefull to the site. I love to have you around.
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On May 20 2010 15:05 Kwidowmaker wrote:
This kept me up a bit last night. If a and b are positive integers, prove that sqrt(a) + sqrt(b) is rational if and only if a and b are perfect squares
well you need only two pieces, the fact that the square root of any integer that isnt a perfect square is irrational, and that anything added to an irrational number is still irrational
so conversely, it's rational only if both terms are square roots of perfect squares
i dont know any algebraic or formal proofs though
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On May 20 2010 22:16 coltrane wrote:Show nested quote +On May 20 2010 12:52 dangots0ul wrote:On May 20 2010 10:37 coltrane wrote:On May 20 2010 09:59 Djzapz wrote:
Since this is solved, I have a fun one (it was for me!)
A truck is on the highway at a constant speed of "s" km/h. The truck's gas consumption is shown by:
q(s)= 1/250*((50/v)+v) in litres/km.
The driver is paid $35/hour.
Find at which speed the cost is at the minimum for the employer for a 254 kilometers drive provided that gasoline costs $1,059 per litre.
It had me confused for a while but it was cewl =D
PS: I'm horrible at math so it took me longer than it should have. that problem is horrible... have you ever thought about the driver's family? or about his rights as a worker? How many hours in a row you want your drivier driving?, have any fkn mba any idea on safety? This is no math, sir, this is pure explotation. edit: On May 20 2010 10:37 dangots0ul wrote:On May 20 2010 10:08 coltrane wrote:On May 20 2010 09:58 dangots0ul wrote:
don't worry bro, you won't be using 99% of this stuff ever after school. unless u go into math Sorry for the double post, but whoever listen this douchebag is a douchebag aswell. And even if he is right, that 1% totally owns. great logic douchebag. 603 shitty oneliners, nothing else to add... clearly some one doesn't know how to go through post history. Its ok, logical reasoning is not for everyone. Someone has got to be the kid sitting in the back with the helmets and seat belts because when I click profile in the upper right corner of your post, and then click the number of posts I dont find 600 one liners about bleach manga... Please stay, you are so usefull to the site. I love to have you around.
15 / 600 definitely = 600 one liners.
clap clap for the special kid!
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On May 21 2010 02:28 SpiritoftheTunA wrote:
well you need only two pieces, the fact that the square root of any integer that isnt a perfect square is irrational, and that anything added to an irrational number is still irrational
so conversely, it's rational only if both terms are square roots of perfect squares
i dont know any algebraic or formal proofs though
That's not actually true. Two irrational numbers added together can in fact be rational.
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On May 21 2010 02:28 SpiritoftheTunA wrote:
well you need only two pieces, the fact that the square root of any integer that isnt a perfect square is irrational, and that anything added to an irrational number is still irrational
That second thing isn't true: sqrt(2) and -sqrt(2) are both irrational but their sum is 0, which is rational. Rational + rational = rational, rational * rational = rational, rational + irrational = irrational, rational * irrational = irrational, but you can't say anything about irrational + irrational or irrational * irrational.
+ Show Spoiler +
Suppose b is not a perfect square, so that sqrt(b) is irrational. If sqrt(a) + sqrt(b) is rational, then (sqrt(a) + sqrt(b)) - 2sqrt(b) = sqrt(a) - sqrt(b) is irrational. Multiplying these gives a - b, which must be irrational, which can't be if a, b are positive integers. So b is a perfect square, and the result follows from symmetry.
EDIT: ninja'd by nineninja :o
On May 20 2010 10:08 coltrane wrote:Show nested quote +On May 20 2010 09:58 dangots0ul wrote:
don't worry bro, you won't be using 99% of this stuff ever after school. unless u go into math Sorry for the double post, but whoever listen this douchebag is a douchebag aswell. And even if he is right, that 1% totally owns.
LOL this is so clever, I'm stealing this. I hear that "math is 99% useless" phrase so much, this is perfect. 
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That's a nice proof.
Could you also say the following?
Since Q is a field, sqrt(a) + sqrt(b) rational implies that if either sqrt(a) or sqrt(b) is rational, then the other must be rational (by closure under addition). Thus, if the statement isn't true, then they both must be irrational. Then use the fact that two strictly positive irrational numbers can never sum to a rational.
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http://www.wolframalpha.com/
plug problems into there and use show steps =p low level math can all be done and steps shown on wolfram i wish i had this when i was going though algebra and calc.
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On May 21 2010 06:40 semantics wrote:http://www.wolframalpha.com/plug problems into there and use show steps =p low level math can all be done and steps shown on wolfram i wish i had this when i was going though algebra and calc.
Haha I use it for uni level maths sometimes
Well low level but messy stuff like algebra or series expansions that you want to quickly check you got right.
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On May 21 2010 06:30 s h 1 k 4 i wrote:
Since Q is a field, sqrt(a) + sqrt(b) rational implies that if either sqrt(a) or sqrt(b) is rational, then the other must be rational (by closure under addition). Thus, if the statement isn't true, then they both must be irrational. Then use the fact that two strictly positive irrational numbers can never sum to a rational.
Sorry, that doesn't work either. I used the closure of Q over addition and multiplication in my proof, I just didn't explicitly state it. But two strictly positive irrationals can still sum to a rational. Take sqrt(2) and 2 - sqrt(2).
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Oh, that was dumb of me, haha. Thanks for the correction.
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EPT
