Answer:
see explanation
Explanation:
(a)
he has only squared the 2 terms in the parenthesis, that is has not expanded fully.
(b)
(x + 3)²
= (x + 3)(x + 3)
each term in the second factor is multiplied by each term in the first factor, that is
x(x+ 3) + 3(x + 3) ← distribute parenthesis
= x² + 3x + 3x + 9 ← collect like terms
= x² + 6x + 9