'GCSE Maths Practice Exam 2025 – All-in-One Guide to Mastering Your Maths Exam Success!'

To complete the square for a quadratic expression of the form \( ax^2 + bx + c \) where \( a > 1 \), the first step is to factor out the coefficient \( a \) from the terms that involve \( x \). This is crucial because it allows us to work with a simpler quadratic expression in the standard form, making it easier to manipulate.

When you factor out \( a \), you rewrite the expression as \( a(x^2 + \frac{b}{a}x) + c \). This is essential because completing the square involves adjusting the \( x \) terms into a perfect square trinomial. By isolating the quadratic portion, you set up for the next steps, such as finding the term needed to complete the square for \( x^2 + \frac{b}{a}x \).

From here, one could determine the necessary constant to complete the square successfully. However, without factoring out \( a \) first, the subsequent steps become more complex, hindering the ability to properly transform the quadratic expression into vertex form. Thus, starting with the factorization is the appropriate initial step in this process.