Question 76362
That would work since if you distribute {{{-a(-a+1)}}} you get {{{a^2-a}}} or you could also say the factorization is:

{{{a^2 - a = a(a-1)}}} Since you said the GCF of the variables (in this case if the GCF itself) is {{{a}}} so we can factor out an {{{a}}} (instead of {{{-a}}})