数式：\bigint


            <a href="http://exp.frozenlib.net/query?exp=%5cbigint_a%5eb+xdx"><img src="http://exp.frozenlib.net/image?exp=%5cbigint_a%5eb+xdx&amp;size=7&amp;textcolor=000000FF&amp;backcolor=FFFFFFFF" alt="\bigint_a^b xdx" style="border:none;" /></a>

$\bigint_a^b xdx$

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