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You can use any of the following conventions.
int(integrand, variable, lower limit, upper limit)
For example, we type this:
\(\displaystyle \int_a^b{\frac{x^2}{x - 1}}\)
like this:
int(x^2/(x - 1), x, a, b)
integral{a to b} x^2/(x - 1) dx
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These notations also make sense, if you've already defined f(x):
f(x) = x^2/(x - 1)
integral{0 to r} f(x) dx
int[f(x), x = a..b]
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For indefinite integrals, just leave off the limits.
int(x^2/(x - 1), x)
OR
int[x^2/(x - 1) dx]
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