The $2010$ census in a particular area gives us an age distribution that is approximately given $($in millions$)$ by the function

$f(x)=39\mathrm{.}42\mathrm{.}13x-0\mathrm{.}867x^2$

where $x$ varies from $0$ to $9$ decades. The population of a given age group can be found by integrating this function over the interval for that age group.

$($a$)$ Find the integral over the interval $0,9.$

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$($Round to the nearest integer as needed.$)$