Another way to reach this conclusion is to examine the sign of the derivative {{MATH_35}} on the interval {{MATH_36}}: {{MATH_37}} From this factorization it is clear that {{MATH_38}} on {{MATH_39}}, and {{MATH_40}} on {{MATH_41}}. This means that the function {{MATH_42}} is decreasing on {{MATH_43}} and increasing on {{MATH_44}}, and, therefore, has a global minimum at the critical point.