Since x is the number of seconds it took the rock to hit the water, x is the value that we are looking for. When the rock hits the water, it's height is 0, therefore, f(x) = 0. So, we can set the expression on the right equal to 0, and solve for 0. Let's do just that:

We can divide by -16, nothing will happen because 0 divided by anything is 0:

To factor any trinomial in standard form (given below), we must find two numbers that add to "b" and multiply to "c":

So, for this specific question, let's find two numbers that add to -8 and multiply to 9. These are clearly 9 and -1. We can write it in this way now:

Both answers would be valid, but there can't be negative time, so your answer is
"It takes 9 seconds for the rock to reach the water."
Answer:
P(t) = 1000e^(0.01155)t
Step-by-step explanation:
Let the population of barangay be expressed according to the exponential formula;
P(t) = P0e^kt
P(t) is the population of the country after t years
P0 is the initial population
t is the time
If barangay has 1000 initially, this means that P0 = 1000
If the population doubles after 60years then;
at t = 60, P(t) = 2P0
Substitute into the formula
2P0 = P0e^k(60)
2 = e^60k
Apply ln to both sides
ln2 = lne^60k
ln2 = 60k
k = ln2/60
k = 0.01155
Substitute k = 0.01155 and P0 into the expression
P(t) = 1000e^(0.01155)t
Hence an exponential model for barangay's population is
P(t) = 1000e^(0.01155)t