Factoring

9 multiplied by zero = 0 Any number multipled by zero = zero. This is a basic rule of our mathematical system.
(t)(0) = 0. Therefore xy = 0 means that either x = 0 or y = 0 If x and y = 0 then there is no reason to have two variables.
(t + 4)(t -3) = 0  Either (t + 4) = 0 or (t -3) = 0 To determine what t = we set (t + 4) = 0 and (t -3) = 0

To solve the problem we need to know what is the value of t that makes (t + 4) = 0 or (t - 3) = 0. So we set each equal to zero and solve for t: