One endpoint of a segment is (12, -8). The midpoint is (3, 18). Find the coordinates of the other endpoint. Please help

Question

hartnn · Answer

if u have 2 endpoints (x1,y1) and (x2,y2) with (m,n) as mid-point,then u have the relation
m=(x1+x2)/2
n=(y1+y2)/2
from this,can u find (x2,y2)?

anonymous · Answer

well i orginally got (6, 44) for the last endpoint but wasnt sure

hartnn · Answer

thats incorrect,so what u get now?

anonymous · Answer

i dont understand how to use the equation

hartnn · Answer

ok, put m=3,x1=12 and find x2.....can u?

anonymous · Answer

i put in the numbers but i dont understand still

hartnn · Answer

let me do x2 for u,then u try for y2
3=(12+x2)/2
so,3*2=12+x2
so,6=12+x2
x2=6-12
x2=-6
got this?

anonymous · Answer

yeah

hartnn · Answer

so will u try for y2 and give me its value?

anonymous · Answer

i got -y2= -44

hartnn · Answer

18*2=-8+y2
36+8=y2
so y2=44
yup,u also got the same....

anonymous · Answer

so i got it right?

hartnn · Answer

yup,the point is (-6,44)

anonymous · Answer

okay... thank u for the help

hartnn · Answer

welcome :)