Answer
(A + B)² = (A + B) (A + B)
= A² + 2AB + B²
Explanation
(A + B)² = (A + B) (A + B)
To open this bracket or to expand this, we will use one of the two expressions to multiply the other
(A + B)(A + B) = A (A + B) + B (A + B)
= A×A + A×B + B×A + B×B
= A² + AB + BA + B²
Note that AB = BA, so, the expression is better written as
A² + AB + AB + B²
= A² + 2AB + B²
Hope this Helps!!!