the condition that x^4 + ax^3 bx^2 + cx + d is a perfect square,is

A)c^2=ad

B)c^2=ad^2

C)c^2=(ad)^2

D)c^2=(a^2) *d

plzz illustrate the answer...

the answer is c^2=a^2*d.Hints:compare the given biquardratic with the square of an quardratic (for eg(px^2 +qx+r)^2).Equate the coefficients of the corresponding power of x.u will get p=1 ;c=2qr;d=r^2 and a=2q ;now use these relations to get the ans

the answer is c^2=a^2*d.Hints:compare the given biquardratic with the square of an quardratic (for eg(px^2 +qx+r)^2).Equate the coefficients of the corresponding power of x.u will get p=1 ;c=2qr;d=r^2 and a=2q ;now use these relations to get the ans

let x^4 + ax^3 bx^2 + cx + d =(px^2+qx+k)^2

                                            =p^2 x^4+q^2 x^2+k^2+2pqx^3+2kqx+2pkx^2

                                            =p^2 x^4+2pqx^3+x^2(q^2+2pk)+2kqx+k^2.

now just compare the constants of lhs and rhs and try to hunt the answer.