52.5k views
4 votes
Are the lines y = –x – 4 and 5x -5y = 20 perpendicular? Explain.

User Dan Mork
by
5.3k points

1 Answer

7 votes

Answer:

yes

Explanation:

If 2 lines are perpendicular then the product of their slopes = - 1

The equation of a line in slope- intercept form is

y = mx + c ( m is the slope and c the y- intercept )

y = - x - 4 ← is in slope- intercept form

with slope m = - 1

5x - 5y = 20 ( subtract 5x from both sides )

- 5y = - 5x + 20 ( divide all terms by - 5 )

y = x - 4 ← in slope- intercept form

with slope m = 1

Thus product of their slopes is - 1 × 1 = - 1

Therefore the lines are perpendicular

User Tim Babych
by
5.6k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.