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#1 Re: Help Me ! » Derive an Equation....Please Help! :) » 2013-03-10 02:39:00

Solve the second equation for

, the third equation for
and the last equation for
. (Did I read your handwriting correctly?) Now you should have expressions for

Substitute your equation for

into the the first equation (in your picture).

You will see that the resulting equation now contains

, so substitute your expression for
to eliminate it.

Finally, you should be left with an expression that contains

. Substitute your expression for
just like you did for

That should be it.

EDIT: I agree with cmowla. Your handwriting is difficult to read here. If any of your equations contain the letter t or number 3, then I've misread.

#2 Re: Exercises » Evaluate algebraic expression » 2013-03-06 18:21:57

Neither the exercise or me got it

Maybe... You might want to double check that you typed the equation properly in your original post. (Does your textbook really say


are you people mathematicians or proffesors

I'm just some guy from Australia lol. I'm studying at university right now, but I'm definitely not a professor! I'm not even studying to become a mathematician. Though math is needed in a lot of different subjects.

#3 Re: Exercises » Evaluate algebraic expression » 2013-03-06 10:14:55

I'm getting 86 with the algebra solver you linked.

Sorry about my previous post. I subbed into the equivalent expression Wolfram Alpha came up with instead of the original. I don't see any reason the answer should be different though.

Why don't you show your working, Allo?

#5 Re: Help Me ! » How do i write it » 2013-02-20 01:00:36

The brackets just make it clear which part of the sentence you want the "for all" quantifier to apply. In larger sentences you might want to quantify

for some of the equation but not the rest. I guess in this case the brackets weren't needed.

The 'v' and upside-down 'v' you're talking about sound like the symbols for logical disjunction

and conjunction
, respectively. There's a Wikipedia page which includes all these symbols and describes their meaning if you're interested: … al_symbols

(Scroll down about half way for the dis- and conjunction symbols.)

#6 Re: Help Me ! » How do i write it » 2013-02-19 07:13:32

This could be a way to write it:

#7 Re: Dark Discussions at Cafe Infinity » Difference between cents and dollars » 2013-02-07 16:16:42

This is hilarious!

I think they were getting confused not only with dollars and cents, but with kilobytes and kilobits.

#8 Re: Help Me ! » Finding the Compound Interest Rate » 2013-02-01 20:22:25

Thanks for your help, bobbym. I think I misspoke; I wanted the interest rate of an amortized loan.

Anyway, I was able to find an approximation method here.

#9 Help Me ! » Finding the Compound Interest Rate » 2013-02-01 18:35:03

Replies: 3

Given a loan amount L, a term Y (in years) and a fixed monthly repayment P, I want to find (or at least approximate) the compound interest rate R. The loan is compounded monthly, once before each payment.

I've looked into geometric series, though it isn't too easy to solve for the ratio.

I'm using a computer to find the interest rate, so iterative methods are fine.

#10 Re: Dark Discussions at Cafe Infinity » 1? Or not? » 2013-01-30 01:21:00

john_gabriel wrote:

All the phony proofs in favour of 0.999... being equal to 1 are easily refuted:

Interesting paper, John. Though I'll admit I'm skeptical.

In particular, on page 6 you prove that

by induction -- which does make sense to me. Where I start to have my doubts is where you show that

is absurd. Didn't you only prove

for the natural numbers?

#11 Re: This is Cool » I've Reached Infinity! 2 » 2013-01-27 10:21:10

If you mean to say that zero is neither positive nor negative, you're absolutely correct. But '-0' isn't the same as saying 'zero is negative'!

To see why 0 is the same as -0 and +0, imagine +1, +2, and so on, as a line starting from zero, like this:



A negative number is the same as a positive number, except you reverse the line. It's Stays the same length and still starts at zero, but it's flipped. For example, -2 looks like this:


You can imagine "flipping the line" with numbers closer and closer to zero (shorter and shorter lines). But what happens when your line gets so short that it doesn't really have length? (You could say "0 length").

By that stage, you don't really have a line anymore. You have a point which represents zero:


Because it doesn't have any length "flipping" it doesn't change it, so +0 is the same as -0.

#12 Re: This is Cool » A Nice Clock » 2013-01-25 20:24:03

Ten is the the acceleration of Earth's gravity, 9.82 m/s/s. Some versions of this clock have it written as

so it equals 10 exactly.

Eleven is written in hexadecimal. In decimal, we have numbers 1 to 9, but in hexadecimal, as well as 1 to 9 there's 'a' to 'f' so you can keep counting: a equals ten, b equals eleven and so on. The zero at the front of '0b' doesn't make any difference here. It's just like writing the number three (in decimal) as 03.

#13 Re: Coder's Corner » EndIf is If? » 2013-01-24 03:05:06

Here's your main problem:

test2 = TextWindow.Read()
If test2 = "Testing Reply 2" Then

You need to put your test on the same line as the 'ElseIf' like this:

ElseIf test2 = TextWindow.Read()
If test2 = "Testing Reply 2" Then

And immediately after the test, Small Basic is expecting a "Then," just like with the if statements:

ElseIf test2 = TextWindow.Read() Then
If test2 = "Testing Reply 2" Then

Also, you can't test if TextWindow.Read() is equal to the variable 'test2' because you haven't set it to anything yet. But you already set the "test" variable to TextWindow.Read() on the second line of your program. What I think you meant to do is something like this:

ElseIf test = "Testing Reply 2" Then

Finally, with all that thinking, we get this:

test = TextWindow.Read()
If test = "Testing Reply" Then
	TextWindow.WriteLine("This is text.")
ElseIf test = "Testing Reply 2" Then
	TextWindow.WriteLine("This is also text.")
	TextWindow.WriteLine("Sorry, this operation did not perform correctly.")

Line by line, the program says this:
1. Show the user "Testing" (print it out on the screen).
2. Set the variable "test" to whatever the user types.
3. Check if the "test" variable is equal to "Testing Reply" (without quotes). If it is, go to step 4, otherwise go to step 5.
4. Show the user "This is text." (Without quotes, of course!) Then go to step 8.
5. Check if the "test" variable is equal to "Testing Reply 2" (without quotes). If it is, go to step 6, otherwise go to step 7.
6. Show the user "This is also text." Then go to step 8.
7. Show the user "Sorry, this operation did not perform correctly." Then go to step 8.
8. This is the "EndIf." It pretty much says "quit asking all these 'if' questions!"

#14 Re: Coder's Corner » EndIf is If? » 2013-01-22 02:42:45

Works fine over here. Your problem could be that you're entering "testing reply" instead of "Testing Reply".

Can you post some of your code involving ElseIf's?

#15 Re: Help Me ! » probability and counting?? » 2013-01-21 06:42:14

I could only figure out that there's at least


#16 Re: Puzzles and Games » Another variation to the two envelopes puzzle » 2013-01-20 19:44:03

Swapping maximizes expected gain for player A and minimizes it for B.

(Left as an exercise for the reader.)

#17 Re: Help Me ! » Boolean rule #11 » 2013-01-20 16:26:02

I don't think they got it from line 3. With or without that term, the statement is the same:

This is because

#22 Re: Maths Is Fun - Suggestions and Comments » Binary Converter - Leading Zeros » 2013-01-07 10:52:36

Seems pretty good to me. I think it might be a good idea to restrict the range of the numbers so they always fit properly in their boxes. Other than that I can't complain.

Just out of curiosity, why haven't you written this in JS/HTML instead of flash? (I'm not suggesting that you do, I'm just curious).

#23 Re: Jokes » What do you think? » 2013-01-02 18:17:09

It's a rimshot sound. I'd post a link, though I'm not an established member yet. Just Google it and listen to a Youtube video.

#25 Re: Puzzles and Games » Logarithm game! » 2012-12-31 16:36:24

Nah, come on! It's an easy mistake to make. Keep going! smile

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