SOLUTION: I want to ask a queation please check to see if this is correct .If M (-7,-3) is the midpoint of segment PQ and the coordinates of Q and are(6,-3).fine the coordinates of Q .

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: I want to ask a queation please check to see if this is correct .If M (-7,-3) is the midpoint of segment PQ and the coordinates of Q and are(6,-3).fine the coordinates of Q .       Log On


   

Question 74263: I want to ask a queation please check to see if this is correct .If M (-7,-3) is the midpoint of segment PQ and the coordinates of Q and are(6,-3).fine the coordinates of Q .
Please see if my problem is correct .Thanks .
M(-7,-3)(6,-3)
7=3= -10 6/3=2
so if -10*2=20
so the P IS -20.-3
Answer by Cintchr(481) About Me  (Show Source):
You can put this solution on YOUR website!
P = (x , y)
M = (-7 , -3)
Q = (6 , -3)

Midpoint = ( +%28x1+%2B+x2%29%2F2 , +%28y1+%2B+y2%29%2F2+ )
work the X values first
+-7%2F1+=+%28x%2B6%29%2F2+
Cross multiply
+-14+=+x+%2B+6+
subtract 6
+-20+=+x+

Now work the Y values
+-3%2F1+=+%28y+%2B+-3%29%2F2+
Cross multiply
+-3%282%29+=+y+-3+
multiply
+-6+=+y+-+3+
add 3
+-3+=+y+

Midpoint = (-20 , -3)

Your method does work as well since the Y coordinates are the same, the line is a horizontal line. Your method will not work unless the line is horizontal or vertical.