Question

write the equation of the passing through the point (6,-8) and perpendicular to the line y=(-5/8)x+25.

Answer 1

The slope of the line you want to be perpendicular to is (-5/8), so the slope of the line that you want is 8/5. That is because the product of the slopes of perpendcular lines must be -1.

So your line must be of the form

y = (8/5) x + C

Choose C so that it passes through the point (6, -8)

-8 = (8/5)*6 + C
C = (-40 -48)/5 = -88/5