1. **Problem a:** Solve the equation $x(x - 4) = 0$. 2. The zero product property states that if $ab=0$, then either $a=0$ or $b=0$. 3. Applying this, set each factor equal to zero: $$x=0$$ $$x-4=0$$ 4. Solve the second equation: $$x=4$$ 5. So, the solutions are $x=0$ and $x=4$. This completes the solution for the first problem.