1. The problem statement, all variables and given/known data Show that x3 - 15x + 1 has three zeroes in the closed interval [-4,4]. 2. Relevant equations I think it's just subbing. 3. The attempt at a solution Well, with that range, I think I can just list them as so: -4 -3 -2 -1 0 1 2 3 4 From here, I figure out an answer by subbing each into each. And through the intermediate value theorem, if 2 numbers have a 0 between them, that should prove one zero is present. I continue this until I discover 3. So first, I when subbing in -4, I get: -64 + 50 + 1 = -3 Subbing in -3 for x, we get: -27 + 45 + 1 = 19 So there must be a 0 between -3 and 19. Thus, I have found one, I continue until I find 2 more? Am I doing this question right? Thanks for the help!