5x^2/x-1-5x=5x^2-5x(x-1)/x-1=5x^2-5x^2+5x/x-1=5x/x-1
4m^2/3-m+4m=4m^2+4m(3-m)/3-m=4m^2+12m-4m^2/3-m=12m/3-m
8n/2-n-4n=8n-4n*(2-n)/2-n=8n-8n+4n^2/2-n=4n^2/2-n
3a-6a^2/2a+5=3a(2a+5)-6a^2/2a+5=6a^2+15a-6a^2/2a+5=15a/2a+5
12b/6-b-2b=12b-2b(6-b)/6-b=12b-12b+2b^2/6-b=2b^2/6-b=2b^2/6-b
14a/2-a-7a=14a-14a+7a^2/2-a=7a^2/2-a