Choose the correct factorisation of (m²−6m).

Correct answer: m(m−6)

The direct answer is B: m(m−6). Both terms, m² and −6m, contain m as a common factor. Taking m outside leaves m from m²÷m and −6 from −6m÷m, so m²−6m=m(m−6). Verification by expansion gives m·m+m·(−6)=m²−6m. Option A has the wrong sign: m(m+6) expands to m²+6m. Option C expands to 6m−6 and is not equal to the original quadratic expression. Option D is a square of a binomial; its expansion is m²−12m+36, which has an incorrect middle term and an extra constant term. A useful habit is to carry the sign of each term into the bracket when taking out a positive common factor. The minus sign belongs before 6 inside the bracket, not outside as an accidental change.