anonymous one year ago Find the equation of the line that is perpendicular to the graph of y=1/2x + 9 and passes through (8,-5)

1. anonymous

Hi --- I can help you with this. First of all, can you tell me what the slope of your line is? $y = \frac 12x + 9$

2. anonymous

slope is 1/2

3. anonymous

Good! Now, can you tell me what the slope of a *perpendicular* line would be?

4. anonymous

would it be the reciprocal?

5. anonymous

Close. The *negative reciprocal". For example, a line of slope 5 would have perpendicular slope -1/5. As a second example, a line of slope -1/3 would have slope 3. So ... what's the slope of your perpendicular line?

6. anonymous

You need to "flip" AND change the sign ...

7. anonymous

-2?

8. anonymous

Good! So now, you want the line with slope -2 that passes through the point (8,-5) . (If you've heard of point-slope form, that would be great to use right now! Or, you can certainly do it different ways...)

9. anonymous

I got y = -2x + 11

10. anonymous

That's what I got, too! Awesome!

11. anonymous

Thank you!!! Really helped!

12. anonymous

You're welcome! Have a great day...