tommykins
i am number -e^i*pi
- Joined
- Feb 18, 2007
- Messages
- 5,718
- Gender
- Male
- HSC
- 2008
We'll fight to the death of solve numerous mathematical questions over it.lyounamu said:You may do so on boys, not chicks as they are already reserved.
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We'll fight to the death of solve numerous mathematical questions over it.lyounamu said:You may do so on boys, not chicks as they are already reserved.
No, that's unfair!!! I will get nailed by you!!!tommykins said:We'll fight to the death of solve numerous mathematical questions over it.
Both our penis sizes will require microscopes so that's out of it.lyounamu said:No, that's unfair!!! I will get nailed by you!!!![]()
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Why not do something that will test our manliness???![]()
1) a, ar and ar^2foram said:Okay solve this:
(i'll post the answer later.)
Three numbers are consecutive terms in a geometric series.
Their sum is 58.5 and their product is 3375.
i) Write down a relationship (using the symbols a and r) which shows that the numbers are consecutive terms in a geometric series.
ii) Find the three numbers.
I am not sure about that.tommykins said:Both our penis sizes will require microscopes.
Yeah, true - it'd just be yours.lyounamu said:I am not sure about that.
i ) a, ar, ar²foram said:Three numbers are consecutive terms in a geometric series.
Their sum is 58.5 and their product is 3375.
i) Write down a relationship (using the symbols a and r) which shows that the numbers are consecutive terms in a geometric series.
ii) Find the three numbers.
Lol. I'll fight you with a shuffle battle [I've seen your sigtommykins said:We'll fight to the death of solve numerous mathematical questions over it.
If you want me to post up working out I will be glad to but it is a quite a long working out.lyounamu said:1) a, ar and ar^2
2) r = 2.5 and a = 6
6, 15 and 37.5
I cannot be bothered to put up my 20 lines of working but I used simultaneous equation where I went a^3 . r^3 = 3375
(a(1 + r +r^2))^3 = 58.5^3
Oh god, shuffle battles are for like the biggest losers out there.Razizi said:Lol. I'll fight you with a shuffle battle [I've seen your sig).
Your solutions are correct.lyounamu said:Did I get it right or what? I think I did. If I did, I will post my working out since it will be pointless to put one if I got it wrong.
Thanks. Here is my working out if anyone didn't knowtommykins said:Your solutions are correct.
My approach was a³r³ = 3375 => ar = 15
a = 15/r
sub it into a+ar+ar², solve quadratic, resub into ar = 15.
Of course you got the answer, but watch out with those decimals, try to do the most simplest working out as to prevent any unncessary errors.lyounamu said:Thanks. Here is my working out if anyone didn't know
Let the 3 numbers be a, ar and ar^2
The product of 3 numbers is: a^3 . r^3 = 3375 ....(1)
The sum of 3 numbers is: a + ar + ar^2 = a(1+r+r^2) = 58.5 ... (2)
(2)^3: a^3(1+r+r^2)^3 = 58.5^3 (200202.625) ... (3)
(3) divided by (2): (1+r+r^2)^3 / r^3 = 59.319
1 + r +r^2 / r = 3.9
r^2 +1+r = 3.9r
r^2 -2.9r +1 = 0
Therefore, r = 2.5 (I used the quadratic formula and r > 0)
I substituted r = 2.5 into the equation (1) to find what a is equal to.
It was an easy question. I thank you for great revision question, Foram!!!
Thanks. I actually did mistake during my working out (with the decimal ones!!!, what a prediction!). I better do another 100s of those over again not to make a mistake.tommykins said:Of course you got the answer, but watch out with those decimals, try to do the most simplest working out as to prevent any unncessary errors.
That's pretty smart too!foram said:Solution:
Let the terms be a/r , a , and ar
Therefore the product is a^3 = 3375
Therefore a=15
Sum= a/r + r + ar = 58.5
=15/r + 15 + 15r = 58.5
15 + 15r + 15r^2 = (58.5)r
15r^2 -43.5r +15 = 0
r= 2.5 or 0.5
Hence series is 6, 15, 37.5 or 37.5, 15, 6
If the series is written as a, ar, ar^2
then (ar)^3
ar=15
a=15/r
15/r + 15 + 15r = 58.5 as stated before.
EDIT: Good work solving it. It was on my 2U half yearly. It was a few easy marks for me, but other people couldn't do it.When I did it, I let the series be a/r, a, ar, but I guess it works the other way too.
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This thread may pass away...but sum things never give way...and go on...forever and everlyounamu said:I reckon this thread is dead. It is tragic that this thread passed away...