If the two pairs of lines $2x^2+6xy+y^2=0$ and $4x^2+18xy+b{y}^2=0$ are equally inclined, then b= 

Both the pairs have same pair of angular bisectors

equation of angular bisector is$3(x^2-y^2)=(2-1)xy.............1$

equation of angular bisector of second equation $9(x^2-y^2)=(4-1)xy$

both equations represent same