Answer:
B. 1
Step-by-step explanation:
Your answer for A is correct.
The time it take for the sub to hit the water will be the time between when the submarine started to get lowered and when its distance from the water was zero.
The sub started to get lowered at x = 0.
Now we need to solve for the smallest positive zero of the function.
This function factors to (x - 1)(x - 7)
From this we can tell that the submarine is a water level for time x = 1 and x = 7.
The smallest of these is 1, so that is when the submarine first hit the water and 7 is when it came back out.
The sub started getting lowered at x = 0 and hit the water at x = 1 and because x is in seconds, it took 1 second for the sub to hit the water.
