Line PR has an endpoint at (25, -5) and a midpoint of (18, -1). What is the value of the x-coordinate of the other endpoint?

Question

campbell_st · Answer

ok... do you know the midpoint formula?

anonymous · Answer

m=x-x/y-y ?

campbell_st · Answer

not quite

there is a formula for x and y... 

basically its the average of 2 x values and average of 2 y values

$$x_{m} = \frac{(x_{2} - x_{1})}{2}$$

$$y_{m} = \frac{ (y_{2} - y_{1})}{2}$$

so you have$$ x_{m} = 18.........y_{m} = -1$$

anonymous · Answer

for points with co-ordinates (x1,y1) and (x2,y2) midpoint (x,y)=( (x1+y1)/2,(x2+y2)/2)

campbell_st · Answer

so substituting 
to find x 

$$18 = \frac{25 - x_{1}}{2}$$

and for y

$$-1 = \frac{-5 - y_{1}}{2}$$

just solve for x and y

anonymous · Answer

|dw:1348863721084:dw|

anonymous · Answer

sketch not to scale

anonymous · Answer

just provided for getting an idea

anonymous · Answer

use the sketch and midpoint formula to find your answer