a^2-4b^2+3a-6b
=(a^2-4b^2)+(3a-6b)
=(a+2b)*(a-2b)+3(a-2b)
=(a-2b)(a+2b+3)
4m^2-4m+2n-n^2
=(4m^2-n^2)-(4m-2n)
=(2m+n)(2m-n)-2(2m-n)
=(2m-n)(2m+n-2)
a^2-4b^2+3a-6b
=(a^2-4b^2)+(3a-6b)
=(a+2b)*(a-2b)+3(a-2b)
=(a-2b)(a+2b+3)
4m^2-4m+2n-n^2
=(4m^2-n^2)-(4m-2n)
=(2m+n)(2m-n)-2(2m-n)
=(2m-n)(2m+n-2)