(y-m1x)(y-m2x)(y-m3x)= the given eq.

so we can say that m1.m2.m3=-a/d

and summ. m1m2=b/d

and m1+m2+m3= -c/d

since m1 m2 are complementary we can say that m1.m2=1

so frm the above three relations we easily get the required result.........

its not so difficult ...........may be u r a begginer FOR THIS TOPIC