Answer and explanation

Correct answer: A.

  1. Step 1: Take out the common factor 3: .
  2. Step 2: Difference of two squares: .
Answer
.
Why not the others: : this expands to . : a perfect square gives a middle term, which is not here. : the bracket still contains a difference of two squares.

Practise more Expressions, Formulae and Relationships.

Free questions with an explanation for every one, and full timed National 5 (Scotland) mock tests.