Answer:
$978
Step-by-step explanation:
Given:
To find the maximum amount of profit, differentiate the equation, set it to zero and solve for x. Substitute found value of x into the original equation.
Differentiate equation
[tex]y=-x^2+78x-543[/tex]
[tex]\implies \dfrac{dy}{dx}=-2x+78[/tex]
Set differentiated equation to zero and solve for x:
[tex]\dfrac{dy}{dx}=0[/tex]
[tex]\implies -2x+78=0[/tex]
[tex]\implies 2x=78[/tex]
[tex]\implies x=39[/tex]
Maximum profit
Substitute x = 39 into the equation:
[tex]\implies -(39)^2+78(39)-543=978[/tex]
Therefore, max profit is $978