we know that the product of slopes of perpendicular lines is -1, and we also know that X-axis and Y-axis are perpendicular to eachother.then,why the product of slopes of X-axis and Y-axis isnt -1

That''s becoz the slopes the lines are measured with respect to x axis and the slope of the x and y axis with respect to x axis is 0 and not defined

well.thats the wrong approach to it

Well! thn in which way should we approach.....,

u have considered x and y as the coordinate axis.

if u mmultiply the slopes u get infinity *o form.

which in limiting conditions comes out to be -1

how can infinity in  any condition(limited) become -1,if then what are the limiting conditions ?