Answer: 9
Step-by-step explanation:
Given
The function is 
To make it a perfect square, compare it with 
Here,
So, c must be square of b i.e. 9
Therefore, value of c is 9.
After 10 hours the temperature is shown on the graph as 30 degrees.
50 degrees - 30 degrees = 20 degrees.
The temperature dropped 20 degrees in 10 hours.
Divide the change by the time:
20 degrees / 10 hours = 2 degrees per hour.
Because the temperature dropped, the change would be negative.
The answer is D. -2 degrees per hour.
Assuming c says 1/3x=21, that's the right answer. if you read too quickly you might rush into thinking x=7, but if course it is 63.
