Question

The function f(x) = –x2 + 60x – 116 models the monthly profit, in dollars, a shop makes for repairing windshields, where x is the number of windshields repaired, and f(x) is the amount of profit. Part A: Determine the vertex. What

Answer 1

( 30 , 784)

Explanation:

Answer 2

f(x)=-x^2+60x-116

f(x)+116=-x^2+60x

-f(x)-116=x^2-60x

-f(x)-116+900=x^2-60x+900

-f(x)+784=(x-30)^2

f(x)-784=-(x-30)^2

f(x)=-(x-30)^2+784

So the vertex is the point (30, 784)

Or you could commit to memory that the vertex for a parabola is always:

( -b/(2a), (4ac-b^2)/(4a) )