115k views
1 vote
What is the equation of the line that passes through the point ( -4, 2) and has a

slope of
-2?

User Rodi
by
4.5k points

1 Answer

7 votes

Answer:

The equation is: y = -2x -6

Explanation:

We have the slope which is - 2. This the main form of a straight line equation is: y = mx + c

y = y point (2)

m = slope (-2)

x = x point (-4)

c = constant - this you need to work out!

Firstly we arrange the equation: y = mx + c

We substitute or replace what we already know into this equation. It is like building a puzzle and only the last piece is unknown and we are trying to make this last piece fit into this puzzle.

The only thing we don't know is what c equals to. After substituting, we get

y = -2x + c.

We can further substitute x and y which is the point (-4;2), we then get:

2 = - 2(- 4) + C

and by using simple math by taking the

- 2(- 4) (which equals to +8, since multiplying 2 negative numbers give you a positive number) to the other side which becomes negative, will give you c = - 6.

Then sub C into the equation.

Hope this helps. :)

User Alex Abdugafarov
by
5.0k points