Question

What is the slope of the line perpendicular to `y=8/5x-3`?

Answer 1

`-5/8`

Explanation:

If you multiply the two gradients/slopes together the answer is -1 if they are perpendicular. So if you change the sign and take the reciprocal you have the second gradient.

Answer 2

`"perpendicular slope "=-5/8`

Explanation:

`"the equation of a line in "color(blue)"slope-intercept form"` is.

`•color(white)(x)y=mx+b`

`"where m is the slope and b the y-intercept"`

`y=8/5x-3" is in this form"`

`"with slope m "=8/5`

`"given a line with slope m then the slope of a line"`
`"perpendicular to it is"`

`•color(white)(x)m_(color(red)"perpendicular")=-1/m`

`rArrm_("perpendicular")=-1/(8/5)=-5/8`