Step-by-step explanation:
so, simply, when is c = 0 ?
0 = -0.0166x² + 1.2109x + 41.708
the solution to such a quadratic equation is
x = (-b ± sqrt(b² - 4ac))/(2a)
in our case
a = -0.0166
b = 1.2109
c = 41.708
x = (-1.2109 ± sqrt(1.2109² - 4×-0.0166×41.708))/(2×-0.0166) =
= (-1.2109 ± sqrt(1.46627881 + 2.7694112))/-0.0332 =
= (-1.2109 ± sqrt(4.23569001)/-0.0332 =
= (-1.2109 ± 2.058079204...)/-0.0332
x1 = (-1.2109 + 2.058079204...)/-0.0332 =
= -25.5174459... years
x2 = (-1.2109 - 2.058079204...)/-0.0332 =
= 98.46322904... years
x1 represents then a calculation backwards of 1940 - 25.5 years (≈ 1914) as the estimated starting point with 0 million sold papers.
x2 is the projected year in the future with 0 million dogs papers :
1940 + 98.46322904... = 2038.463229... ≈ 2038
based on this equation it is expected that during 2038 the circulation of weekday newspapers will drop to 0 millions.
