Given the function f(x) = x^4 - 2x^3 - 6x^2 + 3x +1, use intermediate theorem to decide which of the following intervals contains at least one zero. Select all that apply.

Answers:
First option: [-2,-1]
Second option: [-1,0]
Third option: [0,1]
Sixth option: [3,4]
Please, see the attached files.
Thanks.
Answer:
1,2,3 and 6
Step-by-step explanation:
Intermediate theorem is if a continuous function has values of opposite sign inside an interval, then it has a root in that interval. So if we put edges of internal instead of x into the functions:
First choice:
f(-2)=3
f(-1)=-5
Contains at least one zero.
Second choice:
f(-1)=-5
f(0)=1
Contains at least one zero.
Third choice:
f(0)=1
f(1)=-3
Contains at least one zero.
Fourth choice:
f(1)=-3
f(2)=-17
Does not contain any zero.
Fifth choice:
f(2)=-17
f(3)=-17
Does not contain any zero.
Sixth choice:
f(3)=-17
f(4)=45
Contains at least one zero.