Question

According to projections by a organization of​ countries, the population of a certain country​ (in billions) can be approximated by the following function where x=0 corresponds to the year 1990. In what year will the country reach its maximum​ population, and what will that population​ be?
-0.000177x+0.014595x+1.1386

Answer 1

Check your function. as a linear function, it forever gets bigger.

Answer 2

perhaps you meant:
f(x) = -0.000177x^2 + 0.014595x + 1.1386

in that case find the vertex of this quadratic using the method you learned.

Answer 3

I trust that by now you have
(a) found the vertex at (41.229,1.4395)
(b) know how to use that to answer the question