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Question 1202905: the midpoint of AB is M (3, 2). if the coordintes of A are (8, 7). what are the coordintes
Answer by greenestamps(13209)   (Show Source):
You can put this solution on YOUR website!
Incomplete post; presumably you want to find the coordinates of point B.
Instead of using formal algebra, imagine walking along AB from A towards B. M is the midpoint of AB, which is the halfway point of your "walk".
From A to your halfway point M, you have moved from 8 to 3 in the x direction, a change of -5. To get to the end of your walk, you need to go another -5 units in the x direction; that puts you at x = 3-5 = -2.
From A to your halfway point M, you have moved from 7 to 2 in the y direction, also a change of -5. To get to the end of your walk, you need to go another -5 units in the y direction; that puts you at y = 2-5 = -3.
At the end of your walk, you are at (x,y) = (-2,-3).
ANSWER: the coordinates of B are (-2,-3)
If your assignment is to find the answer using formal algebra....
Let the coordinates of B be (x,y). Then according to the midpoint formula....
(x+8)/2 = 3
x+8 = 6
x = 6-8 = -2
and
(y+7)/2 = 2
y+7 = 4
y = 4-7 = -3
Again (of course), point B is (-2,-3)
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