Factorise

[snapper]

Can anyone show me how to factorise am-bm-an+bn

Thanks

[KatieB]

am-bm-an+bn

Use factorising by grouping. Just look at the first two terms and pull out a common factor of m then the last two terms and pull out a common factor of -n

so am-bm-an+bn ≡ m(a-b) - n(a-b)

now (a-b) is a common factor to both terms so pull this out.

so am-bm-an+bn ≡ m(a-b) - n(a-b)
≡(a-b)(m-n)