Answer:
12
Step-by-step explanation:
x^2 - a
If a is a perfect square we could factor
x^2 - b^2 = (x-b)(x+b)
So a cannot be 36,49,81 since they are perfect squares
a must be 12
For this case we have the following function:

By the time the stone is thrown, x = 0.
We must evaluate this value of x in the function.
We have then:
Answer:
The height of the stone at the time is thrown is given by:
h (0) = 15 meters
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