Question 893236
Find the value of the function at the two endpoints.
{{{f(-1)=9(-1)^4-10(-1)^3-3(-1)-9=9+10+3-9=13}}}
{{{f(0)=9(0)-10(0)-3(0)-9=-9}}}
Since the value of the function was positive 13 and then became negative 9,  somewhere between x=-1 and x=0, the function had the value of zero.