Respuesta :
The amount of units that must be sold to a number yields a maximum profit is 600. Hence 600 units will be the correct option.
How to find maxima?
To find the maxima of any function it needs to differentiate with respect to the dependent variable and equate with zero to get stationary points.
After achieving the stationary points it needs to put on the double derivative of that function to check whether it's maxima or minima.
If the double derivative got negative then it will be maxima.
Given that function
f(x) = -0.001(x-600)² + 90
By differentiation
[tex]$f'(x)$[/tex] = -0.002(x - 600) + 90
Now equate with zero
-0.002(x - 600) + 90 = 0
x - 600 = 0
x = 600
Now checking the x at double derivative
[tex]$f''(x)$[/tex] at x = 600 it is coming out to -0.002 which is negative Hence, the 600 units will be the correct answer.
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