1. Let's start by understanding the problem: you want to verify why the answer key says the answer is 0. 2. Since you didn't provide the exact problem, let's consider a common scenario where the answer is 0, such as solving an equation or evaluating an expression. 3. For example, if the problem is to solve $x^2 - 4x + 4 = 0$, we use the quadratic formula or factorization. 4. Factor the quadratic: $$x^2 - 4x + 4 = (x - 2)^2$$ 5. Set the factor equal to zero: $$ (x - 2)^2 = 0 $$ 6. Solve for $x$: $$ x - 2 = 0 \Rightarrow x = 2 $$ 7. The solution is $x=2$, not 0, so this is just an example. 8. If the problem involves evaluating an expression like $x - x$, the answer is 0 because subtracting a number from itself yields zero. 9. Please provide the exact problem for a precise explanation.