Prove that if one of the line of ax²+2hxy+by²=0 bisects the angle between axes then a+b=+-2h

If one of the line bisects the angle between the perpendicular axes then it's eqn must be; x=y or x=(-y)  thus putting the value of X in the given eqn we get; ay^2±2hy^2+by^2=0

or, a ± 2h +b= 0

Or, a + b = ±2h 

Hence proved