
Answer:
 5 months
Step-by-step explanation:
We assume that y represents production capacity, rather than increase in production capacity. Then we want to solve the 6th-degree equation ...
 x^6 -25x^4 +199x^2 -4975 = 0
This can be factored in groups as ...
 x^4(x^2 -25) + 199(x^2 -25) = 0
 (x^4 +199)(x^2 -25) = 0
This has 4 complex solutions and 2 real solutions.
 x^2 = 25
 x = ±5
The duration required for capacity to reach 4975 units is 5 months.