If x2+1x^2+1x2+1 is a factor of x4+ax3+bx2+cx+dx^4 + ax^3 + bx^2 + cx + dx4+ax3+bx2+cx+d, what is the relationship between coefficients?
a=ca=ca=c and b=d+1b=d+1b=d+1
a=ca=ca=c and b−d=1b-d=1b−d=1
a=ca=ca=c and d=b−1d=b-1d=b−1
c=ac=ac=a and d=b+1d=b+1d=b+1