How to write math formulas like integrals, exponents and fractions in Yahoo! Answers?

Answer 1

As mentioned, you can use the character map to find mathematical symbols. You can also install the quick unicode input tool from http://www.cardbox.com/quick.htm -- it's saved me a lot of time when searching for mathematical symbols. Here are some of the ones I use most often:

√ -- alt-8730
∛ -- alt-8731
² -- alt-0178
³ -- alt-0179
° -- alt-0176
· -- alt-0183
× -- alt-0215
÷ -- alt-0247
± -- alt-0177
∫ -- alt-8747
∬ -- alt-8748
∭ -- alt-8749
∑ -- alt-8721
∏ -- alt-8719
→ -- alt-8594
∞ -- alt-8734
≈ -- alt-8776
≠ -- alt-8800
≡ -- alt-8801
π -- alt-0960
θ -- alt-0952
φ -- alt-0966
δ -- alt-0948
ε -- alt-0949
∈ -- alt-8712
∀ -- alt-8704
∃ -- alt-8707
∠ -- alt-8736

And of course, if you don't remember the proper alt-code for a given symbol, pressing alt-. (the dot on your keypad) will being up the character map automatically if you have the unicode input tool installed, which is a huge improvement over having to go digging into your accessories menu every time you need to look up a symbol. Further, if you find a symbol on the character map that you want to use more frequently, you don't necessarily have to convert the code to decimal - the quick unicode input tool allows you to input the hexadecimal code directly. For instance, I can also input ∑ as alt-.2211 (the dot is very important, since it tells the program you're using the hex code). All of this is explained on the website.

Have I hyped the quick unicode input tool enough yet? Well, let's discuss some notes on notation. Fractions are easy enough to input, just use the standard division slash: / . Thus

a
--
b

can be input as a/b. A word of caution though: the division sign only applies to the argument immediately to the right of it - thus if you write a/bc this means (a/b)*c and not a/(bc), so if your denominator contains more than one term, you must put parentheses around it. This, by the way, brings me to the golden rule of writing math on the internet: if you're not sure whether an argument needs parentheses, put parentheses around it. If you have them, and don't need them, the problem still gets solved, but if you need them and don't have them, people may not be able to figure out what the problem actually is.

By the way, this rule is broken frequently on Y!A, much to my annoyance.

Addition and subtraction are written as you would expect. Multiplication is written by juxtaposition in most cases (that is, simply writing the variables next to each other), but can be written explicitly using an asterisk if necessary to seperate variables or otherwise clarify the problem. Order of operations remains important: a+b*c+d is a+(b*c)+d, not (a+b)*(c+d). You probably already knew that, but you would be amazed at the number of people who don't.

Occasionally, the symbols · or × are also used to indicate multiplication (the latter in grade school arithmetic), but since they are more difficult to key in, the asterisk is used far more frequently, and the above symbols are reserved for the dot and cross products, respectively.

Exponents are, in the general case, written using the caret (^) symbol. Specifically, a to the bth power is written a^b. Exponentiation has the highest priority in the order of operations, so ab^2 is a(b^2), not (ab)^2. Similarly, because it has the highest priority, the expressions a/b^2 and a/(b^2) are equivalent, because the b^2 is evaluated first, before the division sign. For the same reason, a^2b is (a^2)b, not a^(2b). If you want to indicate an exponent which is a product or sum, you must put parentheses around it.

In the special cases of squaring or cubing numbers, it is both permissible and encouraged to use the superscript characters ² and ³, respectively (that is, to write a² for a^2 and a³ for a^3). However, for powers of four or higher, the use of superscript is discouraged -- many browsers do not support the unicode characters for higher superscripts (⁴ ⁵ ⁶ ⁷ ⁸ ⁹ -- these are superscript 4 through 9, respectively. On my system, the superscript 4 shows up, but with very odd spacing. The superscript 5, 6, 7, 8, and 9 show up in a completely different font in IE v7 (which is what I'm using to write this) and did not show up at all in IE v6, so I suspect that most people are simply seeing so many boxes).

To write variables with subscripts, the standard notation is to use an underscore to seperate the variable and its subsript, like this: a_1. If the subscript contains multiple characters, it is advisable to put parentheses around it. For instance, we might write a_(n+1) = a_n + a_(n-1), a_0=1, a_1=1 (this is the definition of the fibonacci series).

To write indefinite integrals, you use the long s just as you would when writing them by hand: ∫f(x) dx. Writing definite integrals is a little trickier -- there's no standard notation for writing the limits of integration. I have adopted the convention of writing the limits of integration immediately to the left of the long s in square brackets. So the definite integral from a to b of f(x) with respect to x is written:

[a, b]∫f(x) dx

While this is not a standard notation, I have never once during my time at Y!A seen someone who has misinterpreted it, or was unable to understand it, so it seems to be a good notation to use. I have adopted a similar convention with sigma notation and limits. To write the sum of the first n squares, for instance, I would write:

[k=1, n]∑k²

And with limits, I write the variable and constant in square brackets immediately to the left of the lim (where they would be written underneath it on paper). So we have:

[x→0]lim (sin x)/x = 1

I hope this has been of assistance.

Answer 2

Magic! (Just kidding!) This is copied from Microsoft Help: "Fraction: \f(,) Creates a fraction with the numerator and denominator centered above and below the division line, respectively. If your system uses a comma as the decimal symbol, separate the two elements with a semicolon (;)." No idea what it means. I think you type the numerator, put "/f(,)", and then the denominator. But I think you have to have an automatic formatter specifically for equations turned on.

Answer 3

What a great answer by matahari!

She should win a T-shirt! One that says:

13
∫ 2x dx
10

Answer 4

You can find symbols in your character map and then copy and paste them. If you are using windows, its in programs/accessories/system tools in your start menu. I'm not sure if they have the symbols for intergrals or derivatives, but they have the square root symbol and other math symbols.
Here are some:
∑ √ ≤ ≈

Answer 5

http://www.micropress-inc.com/fonts.htm