## Mathhelp346 3 years ago Write an equation that contains the given point and is perpendicular to the given line: (4,-1), y=-8

1. Mathhelp346

I tried \[y-y _{1}=m(x-x _{1})\] but i would always get a value for y which isnt right

2. tejasree

I think it is x = 4, thats the equation

3. Mathhelp346

how did you get that

4. tejasree

y = -8 is a horizontal line, the line is perpendicualr to a vertical line, get it?

5. Mathhelp346

yea

6. tejasree

so with a vertical line, x will equal one number, in this case, it is 4, always 4 for any y, so its x = 4, did i confuse u?

7. Mathhelp346

well how did you get x=4?

8. tejasree

it said that it has to contain (4, -1) so that's how I figured that x has to equal 4

9. tejasree

Some points of x = 4 are: (4,2)(4,8),(4,-6).......so one....understand?

10. Mathhelp346

so you just took the 4 from the pair?

11. tejasree

yup, if i included another x-value along with the pair we have, its not going to be perpendicular, that's why

12. Mathhelp346

oh ok thanks

13. tejasree

yea! Thanks :)