hi...about mathemtics

we all know that,multiplication of slope of perpendicular lines is -1.
example....two complex lines are there....1)x+y=2
2)x-y=1....true for this.....but
so is it applicable for x and y axis...
slope of x axis=0
slope of y axis=infinite...
so 0xinfinite=-1...think?
& help if u find any solution..
thanks........

Consider inner product instead.

Vector for x-axis is (x, 0).
Vector for y-axis is (0, y).
Inner product of these is zero.

You can't define slope for y-axis.