Answer :
hello :
the line parallel to the x-axis if : ( a = 0 and b ≠ 0)
for exemple : a = 0 and b= 3 the line has the equation ; y = 2
the line parallel to the x-axis if : ( a = 0 and b ≠ 0)
for exemple : a = 0 and b= 3 the line has the equation ; y = 2