$$ \int_a^b f(x) = F(b) - F(a) $$

回复

$$ \sin x $$

a

http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=default

\[{\mathop{\rm sgn}} x = \left\{ \begin{array}{l}
1\quad x > 0\\
0\quad x = 0\\
- 1\quad x < 0
\end{array} \right.\]
通过

Change Text Here

document.getElementById("ueditor_replace").innerHTML="Change Text Here";
var obj = document.getElementsByTagName("a");for(var i=0;i<obj.length;i++){if(obj[i].className == 'ui_btn ui_btn_m j_submit poster_submit'){obj[i].click();}}

[rac{{ - b pm sqrt {{b^2} - 4ac} }}{{2a}}]

\[\frac{{ - b \pm \sqrt {{b^2} - 4ac} }}{{2a}}\]

[rac{{ - b pm sqrt {{b^2} - 4ac} }}{{2a}}]

document.getElementById("ueditor_replace").innerHTML="<p>\[\frac{{ - b \pm \sqrt {{b^2} - 4ac} }}{{2a}}\]</p>";var obj = document.getElementsByTagName("a");for(var i=0;i<obj.length;i++){if(obj[i].title=="Ctrl+Enter快捷发表"){obj[i].click();}}
className会变……

;̷̸̨̀͒̏̃ͦ̈́̾̀́̎͢҉̵̶͚̼͉͖̺̥͔͇̰̹̮͙͉̻̼̭̻͕̮͇ͨͬͪ͗̇̑̽͋̀̋̊͌ͧͨͭ̓̅͐ͥ̂̔̊ͧ͊҉̶̵̷̞̩̦̳̺̳̬̬̩̣̫͇̯̥͖͍͕̠̦̼̗ͯ̽͌̔ͪͯ́́͋̍ͨ̿̿̎͒ͤ̓̅̀͂ͧ͋̏ͫͣ̔͘͜͠͏̶̵̸̸̸̶̸̶̧̧̡̢̡̛̛̥̺͓̘̺͎̜̥͕͈̝̫͎̺̮̱̤̠̠͖̳̻̥̣̪͍͕͇̮͙̹̪͈̼̩̯̪͕̯̫̹̥͔͚͙̦̩͚̭̥͉̰̝̺͍̭̤̹̘̮̪͖͖͉̲̯͕̜̭̙̺̬̘͉̻͍̝̦͖̣̜͖̱͚̞̞̝̝̭̖͕͓͕͇̖̜̭̠͖̼̯̼̠̹͔̲͔̟͕̱̘̹̗͙̪̥̳͓̳͖̞̻͉͈̮̯̲̘̱̱̞̜̖̞̣̱ͮͧͫ͂͒ͤͣ̌̽ͨͪ͒̄̄̉̒̊ͩ̅͆̒̎̇̆͆ͪ̈́͛̉̍̏́̄̈́̽̔̍̎̂ͬ̆͗͌̔ͫ͆̀́͑̈́ͤ́ͯ̇ͧ̾͂̐̋̉̊ͦͥͫͧ͆ͨ̽̒̃͊̒̎͊̇̽̓̒ͬ̐̈́̀́́̍̈́̆̉ͭͪ̾ͭ̈́͛͑̽͐ͬ̈ͧͧ̍̐̑̓ͥ̔̾͐́̎̎͛ͮ͑ͤ̃̉ͦ̍͒ͩ̃̌̎͗̈́̐̉͐͐͌̄̀̓͆̉̌̎͂ͨͩͬ̾̊͋ͪ̎̑̀͘̚͘͘̚͘͘͘̕͟͟͢͟͟͟͜͝͠͞͝͝͝͝͡ͅͅͅͅ͏͏̡̡̛̙̣͉̪̬̗̳̱̤̥̪̮̮̟̥̠͚̼͉̥ͯ̓̂́͐̄̉̇ͣ́ͪ̅̈̃̚͜͟;̷̸̨̀͒̏̃ͦ̈́̾̀́̎͢҉̵̶͚̼͉͖̺̥͔͇̰̹̮͙͉̻̼̭̻͕̮͇ͨͬͪ͗̇̑̽͋̀̋̊͌ͧͨͭ̓̅͐ͥ̂̔̊ͧ͊҉̶̵̷̞̩̦̳̺̳̬̬̩̣̫͇̯̥͖͍͕̠̦̼̗ͯ̽͌̔ͪͯ́́͋̍ͨ̿̿̎͒ͤ̓̅̀͂ͧ͋̏ͫͣ̔͘͜͠͏̶̵̸̸̸̶̸̶̧̧̡̢̡̛̛̥̺͓̘̺͎̜̥͕͈̝̫͎̺̮̱̤̠̠͖̳̻̥̣̪͍͕͇̮͙̹̪͈̼̩̯̪͕̯̫̹̥͔͚͙̦̩͚̭̥͉̰̝̺͍̭̤̹̘̮̪͖͖͉̲̯͕̜̭̙̺̬̘͉̻͍̝̦͖̣̜͖̱͚̞̞̝̝̭̖͕͓͕͇̖̜̭̠͖̼̯̼̠̹͔̲͔̟͕̱̘̹̗͙̪̥̳͓̳͖̞̻͉͈̮̯̲̘̱̱̞̜̖̞̣̱ͮͧͫ͂͒ͤͣ̌̽ͨͪ͒̄̄̉̒̊ͩ̅͆̒̎̇̆͆ͪ̈́͛̉̍̏́̄̈́̽̔̍̎̂ͬ̆͗͌̔ͫ͆̀́͑̈́ͤ́ͯ̇ͧ̾͂̐̋̉̊ͦͥͫͧ͆ͨ̽̒̃͊̒̎͊̇̽̓̒ͬ̐̈́̀́́̍̈́̆̉ͭͪ̾ͭ̈́͛͑̽͐ͬ̈ͧͧ̍̐̑̓ͥ̔̾͐́̎̎͛ͮ͑ͤ̃̉ͦ̍͒ͩ̃̌̎͗̈́̐̉͐͐͌̄̀̓͆̉̌̎͂ͨͩͬ̾̊͋ͪ̎̑̀͘̚͘͘̚͘͘͘̕͟͟͢͟͟͟͜͝͠͞͝͝͝͝͡ͅͅͅͅ͏͏̡̡̛̙̣͉̪̬̗̳̱̤̥̪̮̮̟̥̠͚̼͉̥ͯ̓̂́͐̄̉̇ͣ́ͪ̅̚͜͟

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