In this case, we'll have to carry out several steps to find the solution.
Step 01:
Data:
y = 480 + 3.6x - 0.1x²
Step 02:
quadratic equation:
graph:
if x = 0, y:
y = 480 + (3.6*0) - (0.1)*(0)² = 480
(0 , 480)
if x = 1, y:
y = 480 + (3.6*1) - (0.1)*(1)² = 480 + 3.6 - 0.1 = 483.5
(1 , 483.5)
With the other points, the procedure is the same.
x-intercepts:
(-53.58 , 0)
(89.58 , 0)
y-intercept:
(0 , 480)
vertex:
(18 , 512.4)
That is the full solution.