How do i use the intermediate value theorem to show that a polynomial function has a real zero between ,-2 and -1?

The intermediate value theorem: if we have some continuous function f on the closed interval [a,b] and we have n as any number that's between f(a) and f(b) ( f(a)  ≠ f(b) ), then there's a number c in open interval (a,b) such that f(c) = nif we let  , then we know that f is a continuous function since it is a polynomial.we then find the values of function f at -2 and -1:         here, we have f(-2) < 0 < f(-1) or -80 < 0 < 1; by the theorem i've restated above, n = 0 is between f(-2) and f(-1).the ivt therefore says that there's a number c between -2 and -1 such that f(c) = 0. and when f(c) = 0, we call c a zero of the function f.