# I don't know how to write formulas for integration, power series, etc. in Math.SE [duplicate]

I want to ask questions from calculus but I do not know how to write the formulas; it causes me lots of problems. I do not know to how write power series as there is no option in my keyboard.

Can anybody guide me on how to write integration and power series? I don't know how to write the big equation of geometry. Can anybody help me, or give me some idea, so that I can more easily ask questions about calculus?

• Here is a brief tutorial about MathJax, MathJax basic tutorial and quick reference – kingW3 Aug 7 '17 at 15:31
• Have a look around for Questions (on the main site, Math.SE) about calculus, power series, etc. If you right-click on a formula, and choose the submenu Show Math as ... TeX Commands, a smallish text popup will show you the exact $\LaTeX$ syntax for that expression (which you can cut, paste, and edit to get your desired effect). – hardmath Aug 7 '17 at 18:25
• Click the edit link of a post that contains the formulas and formats you need to see the source code of the text. Press cancle to cancle the edit. And use the context manue as hardmath has described – miracle173 Aug 15 '17 at 21:47

General math formulas require dollar signs around them. Single for inline and double for displayed (the below are displayed)

$1+2=3$ renders as:

$1+2=3$

$$1+2=3$$ renders as:

$$1+2=3$$

# If you want integration:

Use \int for regular integrals. It displays as

$$\int$$

If you want bounds, use \int_{a}^{b}. It displays as

$$\int_a^b$$

To add stuff inside the integral, I recommend the format \int_{a}^{b} f(x)~dx. It displays as

$$\int_{a}^{b} f(x)~dx$$

For double, triple, or quadruple integrals, everything above applies and use \iint,\iiint,\iiiint, which respectively displays as

$$\iint,\iiint,\iiiint$$

For a closed line integral, use \oint, which displays as

$$\oint$$

# For a sum,

please use \sum, not \Sigma. The difference is shown below:

$$\text{\sum}:~\sum\qquad\text{\Sigma}:~\Sigma$$

To add bounds, the same procedure from above applies. For example, use \sum_{n=1}^{5} n^2 to get

$$\text{\sum}:~\sum_{n=1}^{5} n^2\qquad\text{\Sigma}:~\Sigma_{n=1}^{5} n^2$$

If one of your bounds happens to be infinity or negative infinity, use \infty or -\infty. For example, \sum_{n=0}^{\infty} to get

$$\sum_{n=0}^{\infty}$$

And use \int_{-\infty}^{\infty} to get

$$\int_{-\infty}^{\infty}$$

• The difference between \sum and \Sigma is not only what is shown in this posting: $$\sum_{k=0}^n a_k \text{ versus } \Sigma_{k=0}^n a_k$$ The first of these is \sum; the second is \Sigma. The point is that besides the size and shape, there is the issue of positions of subscripts and superscript. $\qquad$ – Michael Hardy Aug 8 '17 at 2:41
• Note that {curly braces} are needed only when more than one object is to be included. Thus in \sum_{k=0}^n or \sum_{k=0}^\infty one needs the braces in {k=0} but one need not write \sum_{k=0}^{n} or \sum_{k=0}^{\infty}. But \sum_{k=0}^{+\infty} is rendered as $\displaystyle \sum_{k=0}^{+\infty}$ whereas \sum_{k=0}^+\infty appears as $\displaystyle \sum_{k=0}^+\infty. \qquad$ – Michael Hardy Aug 8 '17 at 2:45
• @MichaelHardy To the second comment, some people get confused as to whether or not something counts as "one object", and since both ways work in that situation, I thought it better to mention the method that always works. – Simply Beautiful Art Aug 8 '17 at 11:54
• thanks a lot @ simply beautiful art – Lily Aug 8 '17 at 12:44
• Nice list, @SimplyBeautifulArt But there's nowhere you've mentioned that the expressions only render in Mathjax when surrounded on each side by a dollar sign (or two). – amWhy Aug 11 '17 at 23:34
• @amWhy True. I kind of assumed the OP knew generally how MathJax work, given his/her main site content, and was only asking about the integral and sum stuff. – Simply Beautiful Art Aug 11 '17 at 23:51
• Fair enough; but for others encountering this post, particularly new users who are at Calc II level, I can never hurt to mention it. My comment mainly was meant as a compliment regarding your helpful post. – amWhy Aug 11 '17 at 23:54

Between two dollar signs, type your formula as follows: an integral sign is \int ; to add limits to it use \int_a^b; ; to sum write \sum (to which you can append limits as with an integral) to write $x_i^n$ you need x_i^n ; for a fraction write \frac{numerator}{denominator}. Look up LaTeX or MathJax if you need more examples. If you add an extra dollar sign each time, the formula will be on its own line.

• Writing \int_3^5 yields $\displaystyle \int_3^5,$ but if you want $\displaystyle \int_{33}^{55}$ you need {curly braces}, thus \int_{33}^{55}. And \frac 3 5 yields $\displaystyle \frac 3 5$ but if you want $\displaystyle \frac 3 {55}$ or $\displaystyle \frac {33} 5$ then you need to write \frac 3 {55} or \frac {33} 5. $\qquad$ – Michael Hardy Aug 8 '17 at 3:37