Let D1=aba+bcdc+daba−b and D2=aca+cbdb+daca+b+c then the value of D1D2, where b≠0 and ad≠bc, is ________ .
Using C3→C3−C1+C2 in D1 and D2, we have
D1D2=−2b(ad−bc)b(ad−bc)=−2