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  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

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#26 Re: Help Me ! » Functional Equations » 2017-04-14 15:50:24

ABC1234 wrote:

I also need some help on this problem:
Find all functions

that satisfy
for all nonzero x.

I know I'm supposed to substitute (x-1)/x for x, but I don't seem to be getting anywhere with that. Thanks in advance!

Being a homework problem I can give only hint.
In the previous problem you went from A to B and directly returned to A. Now try going from A to B , B to C and from there to A.

#30 Re: Help Me ! » Geometric probability----circles » 2017-04-02 21:00:15

mr.wong wrote:

Thanks  thickhead ,

What  will  be  the  probability  if  A  cannot  get  through  the  centre  of  E  but  B  can  ?

Product of the 2 probabilities integrated over the region gives the required probability.0.08618
http://www.wolframalpha.com/widgets/view.jsp?id=8ab70731b1553f17c11a3bbc87e0b605

#31 Re: Maths Is Fun - Suggestions and Comments » Partial Derivatives » 2017-03-28 01:42:13

I am originally from Karnataka, now staying in Thane ,Maharashtra.

#32 Re: Maths Is Fun - Suggestions and Comments » Partial Derivatives » 2017-03-27 23:36:24

Yes, something similar but the pronunciation is clearly "d" but not "dh" associated with it.

#33 Re: Maths Is Fun - Suggestions and Comments » Partial Derivatives » 2017-03-27 22:03:36

Daabaa is roadside eating place but it has no connection.

#36 Re: Maths Is Fun - Suggestions and Comments » Partial Derivatives » 2017-03-27 20:34:25

Some people used to call it "daabaa"  like "daabaa y by daabaa x'

#38 Re: Help Me ! » Whats the official way to calculate percent difference? » 2017-03-14 18:24:52

Please see bobbym's signature.It says 'In mathematics, you don't understand things. You just get adjusted to them". It is true for percentage.Percentage is defined as (final-initial)/initial *100. If  a quantity changes from 100 to 200 it is 100% increase. From 200 if it comes back to 100 it is only 50% down. It is defined this way to reduce heart attacks resulting from crash in stock market.Actually every body is confused about the definition but is not aware of it.

#39 Re: Help Me ! » Help with an optimization problem.... please. » 2017-03-14 17:15:23

The point is the quickest time calculated on the basis of rowing speed of 2 mi/hr is not valid now since the rowing speed has changed. Now i want to know how you handled the first part so that I can continue from that.It won't help if the 2 parts are disjoint.

#41 Re: Help Me ! » Help on this proof!! » 2017-03-13 20:49:00

Simple. Show that quadrilateral IFBD is cyclic. And use the property of inscribed angle vs.measure of arc.Finished in two lines.

#42 Re: Help Me ! » Help with an optimization problem.... please. » 2017-03-13 18:17:21

I think my solution is clear 9/sqrt(13) matching with your book answer.I never mentioned 9/sqrt(5).And what you did not understand?My post no.8 or the answer?

#43 Re: Help Me ! » Help with an optimization problem.... please. » 2017-03-13 16:10:02

Yes. I am getting

continuing with my previous post#8

#45 Re: Help Me ! » [ASK] About Debit » 2017-03-10 23:41:18

fulfill the tub= fill the tub full ; However that is Indian English.

#46 Re: Help Me ! » Rotten apples » 2017-03-10 15:34:02

That is excellent.but my query was for your posting in #14 removing 4 from A and weighing it (3:3) vs.C.
but in any way Salem_Ohio's start of 8,8,1 is to be admired as it is less taxing and shows the strength of binary division to the core(8 vs 8 ;4 vs 4; 2 vs 2 when rotten apples break down) even though it requires 3 weighings.

#47 Re: Help Me ! » Rotten apples » 2017-03-10 03:47:34

With 7,7,3 how do you deal with 2:2:1 break of rotten apples?

#48 Re: Help Me ! » Rotten apples » 2017-03-09 04:24:14

Hi Salem_ohio,
As I had written earlier I had a wrong start.6:6:5 combination. but you had a better start. 8:8:1
on first weighing if A and B are equal, you conclude either it is all good apples or both lots have 2 rotten apples each.
Go for second weighing 4:4 of any of the lots. Split verdict indicates 1 rotten apple on each side. the third weighing 2:2 is the decider as this apple can not be divided.
My start with  6:6:5 combination was bad  as it gave rise to 0:0:5,1:1:3  or 2:2:1 distribution of rotten apples.on second weighing C lot had to be weighed against A or B with one apple removed.It failed against 2:2:1 distribution. But wait, this also looks plausible.Let us say on second weighing we remove one from B and weigh the remaining 5 with C. a 0:0:5 or 1:1:3 distribution will make it unbalanced.If they are balanced it means it is 2:2:1 distribution and the one removed is a rotten apple. Add it to A to make make it 7 apple lot with 3 rotten apples in it.Add 2 apples from C to B. Now B  may at the most contain 2 rotten apples and will be unbalanced against A in the third weighing.

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