This study notes covers Worked Example 3: Difference of Two Squares within Solving Quadratics for GCSE Mathematics. Revise Solving Quadratics in Algebra for GCSE Mathematics with 15 exam-style questions and 12 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 6 of 8 in this topic. Use this study notes to connect the idea to the wider topic before moving on to questions and flashcards.
Worked Example 3: Difference of Two Squares
Solve: x² - 16 = 0
Step 1 Recognise the pattern
x² - 16 = x² - 4²
This is a difference of two squares!
Step 2 Factorise using a² - b² = (a-b)(a+b)
(x - 4)(x + 4) = 0
Step 3 Solve
x - 4 = 0 → x = 4
x + 4 = 0 → x = -4
Practice questions for Solving Quadratics
The equation x² + 5x + 10 = 0 has:
A rectangle has length (x + 5) cm and width (x + 2) cm. The area of the rectangle is 40 cm². Form a quadratic equation and solve it to find the value of x.