Answer:
51.07 billion virus particles
Step-by-step explanation:
The equation that describes the number, in billions, of flu virus particles in a person's body x days after being infected is:
[tex]y=-0.73x^4+3.1x^3+26.5[/tex]
For x = 3 days:
[tex]y(3)=-0.73*3^4+3.1*3^3+26.5\\y(3) = 51.07\ billion[/tex]
Therefore, after 3 days, there will be 51.07 billion virus particles in a person's body.