Question:
The midpoint of segment AB is P(0, 4). If the coordinates of B are (−2, 3), then the coordinates of A are
(a) $(2,5)$
(b) $(-2,-5)$
(c) $(2,9)$
(d) $(-2,11)$
Solution:
Let (x, y) be the coordinates of A. Then
$0=\frac{-2+x}{2} \Rightarrow x=2$
$4=\frac{3+y}{2} \Rightarrow y=8-3=5$
Thus, the coordinates of A are (2, 5).
Hence, the correct answer is option (a).