I'm not sure if this is the right place to post, sorry if its not:

Problem:
"Each symbol represents a digit.
If %u263B%u263B+ %u29EB%u29EB = %u29EB%u29EB%u25CE; How much is: (%u263B%u263B)*(%u29EB%u29EB)"

I don't have the answer.

Can anyone help me?
I think this should be easy but I haven't studied maths in years.

Ugh,

Try that again:

Problem:
"Each symbol represents a digit.
If AA + BB = BBC; How much is (AA)*(BB)?"

At 1/8/12 04:30 PM, Wronzoff wrote: Problem:
"Each symbol represents a digit.
If AA + BB = BBC; How much is (AA)*(BB)?"

I'm not a member of this club, but I fancy tackling this.

- A + B > 9, otherwise the sum wouldn't go into triple figures.
- When you're summing together single digit numbers, the total isn't going to be larger than 19. Therefore the first digit in the total, B, is 1.
- In order to get A + B > 9 with a single digit for A, A can only be 9.
(So C is 0, and 99+11 = 110)

Final part is 99*11, which equals 1089.

At 1/8/12 04:30 PM, Wronzoff wrote: Ugh,

Try that again:

Problem:
"Each symbol represents a digit.
If AA + BB = BBC; How much is (AA)*(BB)?"

lol

At 1/8/12 04:30 PM, Wronzoff wrote: Ugh,

Try that again:

Problem:
"Each symbol represents a digit.
If AA + BB = BBC; How much is (AA)*(BB)?"

i have a better way. note that the sum of two two-digit number should be less than 200. B=1. since BBC is a three digit number, the only possible value for A is 9. so we are done.

call me a troll if you want, but i never realised that the standards in other countries is that low....

problem:
if possible, find the value(s) of a such that the following system of linear equations has solution(s).

2x+3y=-1
x+4y=2
ax+5y=3.

furthermore, write down the solution(s) if the system of equations is consistent.

At 1/8/12 11:10 PM, i-am-ghey wrote: i have a better way.

Better than what? Cos our method is exactly the same.

At 1/9/12 03:04 AM, i-am-ghey wrote: call me a troll if you want, but i never realised that the standards in other countries is that low....

problem:
if possible, find the value(s) of a such that the following system of linear equations has solution(s).

2x+3y=-1
x+4y=2
ax+5y=3.

furthermore, write down the solution(s) if the system of equations is consistent.

2x+3y=-1
2x=-3y-1

x+4y=2
2x+8y=4
2x=-8y+4

-3y-1=-8y+4
5y=5
y=1
y=2x
x=1/2

0.5a+5=3
0.5a=-2
a=-4

At least, that's what I think.
I don't know if that's a troll question, but at least I got some training in this.

Yup, yet another Maths problem. Differentiation this time - it's a very easy topic but there's one question that the Maths teacher gave us which I don't seem to understand.

---------

A cylinder is cut from a solid sphere of radius 5 cm. If the height of the cylinder is 2h, show that the volume of the cylinder is 2(pi)(h)(25 - h^2), assuming that the curved edges of the cylinder reach the surface of the sphere. Find the maximum volume of such a cylinder.

---------

The answer of the cylinder's max volume is 500(pi)(sqrt(3)) / 9.

My problem with this is that it seems a bit vague. I don't really know where to start. I might just be doing something stupid, I dunno.

Help is very much appreciated.

The maths has started getting much harder very quickly on my course now, mainly calculus. Is there an easy way to remember the process for things like the complimentary function and particular integral?

At 1/25/12 10:30 AM, Supersteph54 wrote:

A cylinder is cut from a solid sphere of radius 5 cm. If the height of the cylinder is 2h, show that the volume of the cylinder is 2(pi)(h)(25 - h^2), assuming that the curved edges of the cylinder reach the surface of the sphere. Find the maximum volume of such a cylinder.

if i understand the question correctly, basically, you need to assume that the height of the cylinder if h first. then use pyth. theorem to find the radius of the base. thus volume of cylinder can be determined. it is helpful to draw relevant diagrams.

for the second part, you need to find the max value of V as h varies. so differentiate the answer to the first part with respect to h and find the absolute maxima.

should not be very hard.

I'll give you guys a challenge. I know what the answer is, but I can't figure out how to derive it:

Given an unlimited supply of 50p, £1 and £2 coins, in how many different ways is it possible to make a sum of £100?

A: 1326
B: 2500
C: 2601
D: 5050
E: 10000

At 1/26/12 06:53 AM, PigeonOnAStick wrote:

question.

don't really want to do it. i prefer leaving it for somebody else.
i assume the order does not matter. that is, no matter how the coins are arranged, as long as the number for each type of coin remains the same, it is counted as one way. tell me if i am wrong.

consider the cases with i 2 dollar coins first. simply find the number of ways possible to make a sum of 100-2i with the remaining coins, and then sum up the cases from i=0 to 50.

At 1/25/12 11:35 PM, i-am-ghey wrote: if i understand the question correctly, basically, you need to assume that the height of the cylinder if h first. then use pyth. theorem to find the radius of the base. thus volume of cylinder can be determined. it is helpful to draw relevant diagrams.

for the second part, you need to find the max value of V as h varies. so differentiate the answer to the first part with respect to h and find the absolute maxima.

should not be very hard.

SO MUCH HELPFULNESS.

Thanks a lot man. My main problem was that I didn't understand how the cylinder was cut off from a sphere, since a cylinder has two flat sides and one round side while a sphere is all round. Even the teacher said that the question was quite vague and needed quite a bit of assumptions.

Anyway, thanks again, managed to work it out easily :3.

At 1/26/12 12:18 PM, PigeonOnAStick wrote:

At 1/26/12 08:33 AM, i-am-ghey wrote: consider the cases with i 2 dollar coins first. simply find the number of ways possible to make a sum of 100-2i with the remaining coins, and then sum up the cases from i=0 to 50.

Thanks for stating the obvious.

i have already done half the steps.
to find n(i), where n(i) is the number of ways possible to make a sum of 100-2i with the remaining coins, let j be the number of 1's, and there can only be one possible way to for that to happen.

for a fixed i, j ranges from 0 to 100-2i, so, the required sum is 1+3+...99=2500. done.

At 1/26/12 08:33 AM, i-am-ghey wrote:

At 1/26/12 06:53 AM, PigeonOnAStick wrote:

question.
don't really want to do it. i prefer leaving it for somebody else.

How considerate. Thanks for the unnecessary post.

consider the cases with i 2 dollar coins first. simply find the number of ways possible to make a sum of 100-2i with the remaining coins, and then sum up the cases from i=0 to 50.

Thanks for the half-assed answer. I've done it now, no thanks to your summation from i=0 to 50 approach.

At 1/26/12 12:27 PM, i-am-ghey wrote:

for a fixed i, j ranges from 0 to 100-2i, so, the required sum is 1+3+...99=2500. done.

missed a 101, yeah should be 2601. silly me.
can't even get a troll question right the first time. don't know if intentional or not.

At 1/26/12 12:43 PM, i-am-ghey wrote: missed a 101, yeah should be 2601. silly me.

There you go, smart guy.

can't even get a troll question right the first time. don't know if intentional or not.

Not trolling, it's just that you responded like an arse.

that was not my intention though. it is just that the solution is obvious to me, and not to everybody here. so i decided to only complete the part of the problem and let others think about it for a while, as the steps as similar.

i wasn't too interested in getting the final answer because it is kinda of tedious. and if i didn't phrase it appropiatate, sorry about that.

are we done?

I hope I'm not getting too annoying.

--------

Given that y = (x^2 - 2x + 1) / (x^2 + 1), find the range of values of y for real x.

--------

I've spent ages trying to figure out what to do in vain, and neither did two of my friends manage to work it out, and they're both good at maths. This question came out in a half-yearly maths past paper of my school and I really need to know how to work it out in case something similar comes out in my exam (which is on Wednesday).

Thanks a lot to the kind soul who helps out.

At 1/30/12 02:00 PM, Supersteph54 wrote: I hope I'm not getting too annoying.
Given that y = (x^2 - 2x + 1) / (x^2 + 1), find the range of values of y for real x.

hint: (x^2-2x+1)/(x^2+1)=1-2x/(x^2+1). now, the problem becomes looking at the range of x/(x^2+1).

there are a number of ways to do it. the first (and rather uninteresting) method is to compute derivatives and try to sketch the curve.

the second method is to use purely algebraic techiques to find the range (more interesting).
let x/(x^2+1)=a, rewriting, we have ax^2-x+a=0. and this equation must have real roots, so...?

At 1/30/12 07:22 PM, i-am-ghey wrote: the second method is to use purely algebraic techiques to find the range (more interesting).
let x/(x^2+1)=a, rewriting, we have ax^2-x+a=0. and this equation must have real roots, so...?

Discriminant must be greater than or equal to 0.

You're a genius. Thanks a lot!

At 1 month ago, PigeonOnAStick wrote:

At 1/8/12 04:30 PM, Wronzoff wrote: Problem:
"Each symbol represents a digit.
If AA + BB = BBC; How much is (AA)*(BB)?"

I'm not a member of this club, but I fancy tackling this.

- A + B > 9, otherwise the sum wouldn't go into triple figures.
- When you're summing together single digit numbers, the total isn't going to be larger than 19. Therefore the first digit in the total, B, is 1.
- In order to get A + B > 9 with a single digit for A, A can only be 9.
(So C is 0, and 99+11 = 110)

Final part is 99*11, which equals 1089.

Hey thanks for the answer and explanation! It was so easy I can't believe I couldn't see it.

At 1 month ago, mothballs wrote:

At 1/8/12 04:30 PM, Wronzoff wrote: Ugh,

Try that again:

Problem:
"Each symbol represents a digit.
If AA + BB = BBC; How much is (AA)*(BB)?"

lol

This forums was dead so I posted on the general too,sorry.

Another problem with Maths. Sorry for posting so many problems but I'd rather get some assistance here rather than go to school with one sum left out.

--------

Find the values of k for which y = x / ((x + 1)^2 (x - k)) has only one stationary value.

--------

I try to differentiate the equation, make that derivative equal to 0 and eventually get a cubic equation in terms of x with k as a constant, equal to 0. I crossed off one of the roots since it didn't have k in it and it's k that I'm interested in (I'm really not sure whether I'm allowed to do this or not haha). I then reasoned it out that for there to be one stationary value there has to be a repeated root, so I considered the discriminant being equal to 0, got an equation in terms of only k and came to the wrong answer (unsurprisingly since I doubt I'm doing this right).

My reasoning is most likely wrong but it may be a numerical mistake - I'm not sure. I'd love it if someone could point me in the right direction, please. I guess it's better to make sure I know differentiation inside out before I start integration. Also I have a differentiation test soon and if something like this comes out in said test, I'll be stumped. D:

Here's a snapshot of my work. I kinda stopped when I reached k(k - 3) = 0 because I knew the answer was wrong. The right answer is 8. Thanks a lot to whoever helps out,

At 9 hours ago, Supersteph54 wrote: Find the values of k for which y = x / ((x + 1)^2 (x - k)) has only one stationary value.

obviously, k cannot be equal to 0, although the equation might suggest so. when k=0, x=0 is the only solution, but the graph is discountinous at that point. when k=3, x=1 is the only solution. and it is also valid because y=f(x) is defined at x=1.

i think the answer should be k=3 only. you cannot have exactly one stationary point for any other values of k.

also, the reason why you can cancel out the (x+1) factor is because x cannot be equal to -1, otherwise, the graph blows up.

At 1 hour ago, i-am-ghey wrote: i think the answer should be k=3 only. you cannot have exactly one stationary point for any other values of k.

actually, there is another possible answer if you can find another value of k so that -1 is the root of the quaratic equation, and the value of k gives two distinct solutions.

you can find the another k by substiting x=-1 in the quaratric equaiton and check every conditions are satisfied. a minor oversight.

Yeah but if you use x = -1 you'll get a division by 0 in the original equation and as you said the graph goes boom... right?

Also the answer is supposed to be 8, not 3. Perhaps I'm doing some sort of numerical mistake but I can't seem to find it. D:

Oh and by the way, thanks AGAIN for all the help you've been giving me. You're definitely one of the reasons I got the highest exam mark in my maths class, which is 90%.

in the fourth line, you forgot the factor (x+1).

the equation should read, 0=(x+1)((x+1)(x-k)-x(x+1)-2x(x-k))/((x+1)^4)((x-k)^2)

and you should get the result k=8.

moreover, k=-1 is the second solution. (case where equaiton has two distinct roots but one of the roots is, -1, other case is similar)

check that f(x)=x/(x+1)^3 has only one stantionary point as well (x=/=-1)the answer is imcomplete.

by the way, here is a problem related to polynomials and differentiation i came up with.

let p(x) be a degree 3 polynomial with real coefficients. given:
1. the leading coefficient of p(x) is 1.
2. r(a)=r(b)=c
3. p(x) is divisible by (x-b)^2.

(a) find the quotient and remainder when p(x) is divided by (x-a)^2.

suppose f(x) is a degree four polynomial satisfying f'(x)=p(x), and f(x) is divisible by (x-b)(x-r), where b and r are roots of
p(x)=0.

(b) show, by considering the graph of f(x) and f'(x), that b=r.

Math is my worst subject!