What is the factorisation of (25p^2-36q^2)?

Correct answer: \((5p+6q)(5p-6q)\)

\(25p^2-36q^2=(5p)^2-(6q)^2\), which is a difference of two squares. Using \(a^2-b^2=(a+b)(a-b)\), we get \((5p+6q)(5p-6q)\). Options A and D are squares of a difference and a sum respectively; their expansions contain a \(pq\) term, which is absent in the given expression. Exam tip: identify the square roots first, then use \((a+b)(a-b)\) for a difference of squares.