-21x+28 is factored into:
-7(3x-4)
- 3 - (- 8) - (- 2) = x
Distribute the negatives to the numbers in the parentheses.
- 3 + 8 + 2
- 3 + 10
7
x = 7
The question might have some mistake since there are 2 multiplier of t. I found a similar question as follows:
The population P(t) of a culture of bacteria is given by P(t) = –1710t^2+ 92,000t + 10,000, where t is the time in hours since the culture was started. Determine the time at which the population is at a maximum. Round to the nearest hour.
Answer:
27 hours
Step-by-step explanation:
Equation of population P(t) = –1710t^2+ 92,000t + 10,000
Find the derivative of the function to find the critical value
dP/dt = -2(1710)t + 92000
= -3420t + 92000
Find the critical value by equating dP/dt = 0
-3420t + 92000 = 0
92000 = 3420t
t = 92000/3420 = 26.90
Check if it really have max value through 2nd derivative
d(dP)/dt^2 = -3420
2nd derivative is negative, hence it has maximum value
So, the time when it is maximum is 26.9 or 27 hours
