Ihave been stuck on it for an hour

in your lab, a substance's temperature has been observed to follow the function t(x) = (x + 5)3 + 7. the turning point of the graph is where the substance changes from a liquid to a solid. using complete sentences in your written answer, explain to your fellow scientists how to find the turning point of this function. hint: the turning point of the graph is similar to the vertex of a quadratic function.