The function \(P(x)=x^3-10x^2+9x-90\), where \(x\) is the number of items sold, models the profit \(P(x)\), in dollars, for Company A. The company breaks even when the profit is $0. How many items must Company A sell to break even?

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We can set the function equal to 0 to find the break even point.

$$ 0 = x^3-10x^2+9x-90 $$

Use the calculator to find the zeroes. Alternatively, through factoring by grouping,

$$ 0 = x^3-10x^2+9x-90 $$ $$ 0 = x^2(x-10)+9(x-10) $$ $$ 0 = (x^2+9)(x-10) $$ $$ x= \boxed{10} $$