On comparing the corresponding coefficients A+C=0......(i) A+B+D=1......(ii) A+B+C=−1......(iii) B+D=1 ......(iv) From Eqs. (i)and (iii), we have B=−1 From Eq. (iv), we have −1+D=1 ⇒D=2 From Eq. (ii), we have A+(−1)+2=1 A=0 From Eq. (i), we have A+C=0 0+C=0 C=0 ∴A+2B+C+2D =0+2(−1)+0+2(2) =−2+4=2