The current population of Dallas, Texas is about 1,260,000 people. The function given below gives the predicted population of Dallas in tyears.
R0 = 920,000(1.12)
About what will the population of Dallas be in five years?
OA. 1,816,000
OB. 1,621,000
OC. 920,000
OD 2,386,000
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if the eqn of the parabola is f(x) = (x-4)(x+2), we need to mult. this out to find the coordinates of the vertex.

then f(x) = x^2 + 2x - 4x - 8, and f(x) = x^2 - 2x - 8.

one way in which you can find the vertex is to calculate x = -b / (2a).   here, that comes to

        )

x = = 1.   f(1) = 1^2 - 2(1) - 8 = - 9.   vertex is at (1, -9).

        2(1) 

find another point on the curve:   let x=0, for which y=-8.   then (0, -8) is on the curve.   plot the vertex and this point and draw a smooth parabola thru both.

hope this