Answer:
b² -2ab +a²
Step-by-step explanation:
The first factor can be rearranged to put the minus sign in the middle. Then you have
(b -a)(b -a) = (b -a)² = b² -2ab +a²
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If you like, you can also write this as ...
a² -2ab + b² . . . . . . terms in lexicographical order
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The "special product" of interest here is the square of a binomial:
(p +q)² = p² +2pq +q²
You have p=b, q=-a, so the result is as shown above.
