Factorise : 2b^2-2b is 2b (b-1)
[tex]2b^2=2\cdot b\cdot b\\\\2b=2\cdot b\\\\2b^2-2b=\boxed{2}\cdot\boxed{b}\cdot b-\boxed{2}\cdot\boxed{b}\cdot1=\boxed{2}\cdot\boxed{b}(b-1)=\boxed{2b(b-1)}[/tex]