If I can at least get how to properly put the function in a calculator that’d be great

Which is a true statement about an exterior angle of a triangle a. it is formed by two segments that are not sides of the triangle, b. it forms a linear pair with one of the interior angles of the triangle, c. it is complementary to one of the interior angles of the triangle. d. it is formed by two segments that are sides of the triangle.

How do i make someone brainliest? (if you answer me, i might be able to make you brainliest! )

Find the roots of the polynomial function f(x) = x^3 + 2x^2 + x