Question

Y=-0.71x^4+2.8x^3+27.4 describes the billions of flu virus particles in a persons body x days after being infected.Find the number of virus particles, in billions, after 4 days

Answer 1

24.84 billion

Explanation:

Put 4 where x is in the equation and do the arithmetic. It can be easier if a little factoring is done first.

y = (-0.71x +2.8)(x^3) +27.4

y = (-0.71(4) +2.8)(64) +27.4

y = 24.84

The formula predicts about 24.84 billion virus particles after 4 days.