Answer
B = (2.5 , -13.7)
Work Step by Step
Given M(2.1,-5.7) is the mid point of $\overline{AB}$, Ponit A (1.7, 2.3)
To find out the coordinates of point B(x2,y2)
use theorem 10.1.2
Midpoint M(xm,ym) =($\frac{x1+x2}{2}$ , $\frac{y1+y2}{2}$)
(2.1,-5.7) =($\frac{1.7+x2}{2}$ , $\frac{2.3+y2}{2}$)
2.1 =$\frac{1.7+x2}{2}$ ,-5.7 =$\frac{2.3+y2}{2}$
x2=4.2-1.7, y2 = -11.4-2.3
x2 = 2.5 , y2 = -13.7
