Question

Point M (2,-1) is the midpoint of CD. If C is (4, -3),
find the coordinates of D.

Answer 1

The coordinates of point D is (6,-5)

the explanation is in the picture, using the midpoint formula

Answer 2

(0,1)

Explanation:

You can look at the picture and graph it out. If I look at the slope from C to M, I will see that it is
`(2)/(2)`. If I continue that pattern, I will be at point D.

Or I could calculate this. I know that the point M is the average between points C and D.

Let's look at x first. The average would be the addition of the two x values divided by 2. So, I could write the equation to solve for x

2 =
`(4 +x)/(2)` Multiply both sides of the equation by 2

4 = 4 + x Subtract 4 from both sides of the equation

x = 0

Do the same thing for y:

-1 =
`(-3 + y)/(2)` Multiply both sides of the equation by 2

-2 = -3 + y Add 3 to both sides of the equation

1 = y