Answer :
[tex]f(1)=-5\cdot1^4+8\cdot1^3+6\cdot1+1=-5+8+6+1=10\\
f(2)=-5\cdot2^4+8\cdot2^3+6\cdot2+1=-80+64+12+1=-3\\\\
f(1)>0\\
f(2)<0\\
\Downarrow[/tex]
It does.
It does.