We have,
(x2+1)(x4+x2+1)4x2+5x4+7=x2+1Ax+B+x4+x2+1Cx3+Dx2+Ex+F⇒4x2+5x4+7=(Ax+B)(x4+x2+1)+(Cx3+Dx2+Ex+F)(x2+1)⇒5x4+4x2+7=Ax5+Ax3+Ax+Bx4+Bx2+B+Cx5+Cx3+Dx4+Dx2+Ex3+Ex+Fx2+F⇒5x4+4x2+7=(A+C)x5+(B+D)x4+(A+C+E)x3+(B+D+F)x2+(A+E)x+(B+F) On comparing, we get
A+C=0B+D=5A+C+E=0B+D+F=4A+E=0B+F=7On solving, we get \begin{gathered}A=C=E=0, B=8 . D=-3, F=-1 \\ \therefore B+2(D+F+E)-C \cdotA=8+2(-3-1+0)-0 \times0 \\ =8-8=0 \end{gathered}