Find the equation of the common tangent to the parabolas y2=4axy^2 = 4axy2=4ax and x2=4ayx^2 = 4ayx2=4ay.
x+y+a=0x + y + a = 0x+y+a=0
x+y=ax + y = ax+y=a
x−y+a=0x - y + a = 0x−y+a=0
x+y+2a=0x + y + 2a = 0x+y+2a=0