(m-1)/(m^2+3m+2)-6/(m^2-m-2)
=(m-1)/(m+1)(m+2)-6/(m+1)(m-2)
=(m-1)(m-2)/(m+1)(m+2)(m-2) -6(m+2)/(m+1)(m+2)(m-2)
=(m^2-3m+2-6m-12)/(m+1)(m+2)(m-2)
=(m^2-9m-10)/(m+1)(m+2)(m-2)
=(m+1)(m-10)/(m+1)(m+2)(m-2)
=(m-10)/(m+2)(m-2)
=(m-10)/(m^2-4)
(m-1)/(m^2+3m+2)-6/(m^2-m-2)
=(m-1)/(m+1)(m+2)-6/(m+1)(m-2)
=(m-1)(m-2)/(m+1)(m+2)(m-2) -6(m+2)/(m+1)(m+2)(m-2)
=(m^2-3m+2-6m-12)/(m+1)(m+2)(m-2)
=(m^2-9m-10)/(m+1)(m+2)(m-2)
=(m+1)(m-10)/(m+1)(m+2)(m-2)
=(m-10)/(m+2)(m-2)
=(m-10)/(m^2-4)