Respuesta :
Answer:
x = 8 years
Therefore, the machine will be profitable to use for 8 years
Step-by-step explanation:
Given;
The rate of annual savings​ (in dollars) given by the function S'(x)​, and the rate of annual costs​ (in dollars) given by the function C'(x).
S'(x) = 142 - x²
C'(x) = x² + (7/4) x
For the machine to be profitable for use, The rate of annual savings​ (in dollars) given by the function S'(x)​ equal to or greater than the rate of annual costs​ (in dollars) given by the function C'(x).
S'(x) = C'(x)
142 - x² = x² + (7/4) x
0 = 2x² + (7/4)x - 142
2x² + (7/4)x - 142 = 0
Multiplying through by 4;
8x² + 7x - 568 = 0
Solving the quadratic equation, we have;
x = -8.875 or x = 8
Since x which is the number of years cannot be negative.
x = 8 years
Therefore, the machine will be profitable to use for 8 years