The correct options are
C α=−1, β=−a
D α=−1, β=a
x2+αy2+2βy=a2 represent pair of perpendicular straight lines
Coeff. of x2+Coeff. of y2=0
1+α=0
α=−1
and Discriminant=D=abc+2fgh−af2−bg2−ch2=0
=−αa2−β2=0
αa2+β2=0
and α=−1,β2=a2
α−1 and β=a or β=−a
Answer is C & D.