The problem asks to expand the expression $(a - b)^2$.

1. Problem Description

The problem asks to expand the expression $(a - b)^2$.

2. Solution Steps

We need to expand $(a-b)^2$. We can rewrite this expression as $(a-b)(a-b)$.

Using the distributive property (also known as the FOIL method), we can expand this as follows:

$(a-b)(a-b) = a(a-b) - b(a-b)$

$= a*a - a*b - b*a + b*b$

$= a^2 - ab - ba + b^2$

Since $ab = ba$, we have:

$= a^2 - ab - ab + b^2$

$= a^2 - 2ab + b^2$

So, $(a-b)^2 = a^2 - 2ab + b^2$.

3. Final Answer

$a^2 - 2ab + b^2$