Question

A segment in the complex plane has a midpoint at 7 – 2i. if the segment has an endpoint at 11 – 3i, what is the other endpoint? –10 –2i 3 – i 9 – 2.5i 18 – 4i

Answer 1

$~~~~~~~~~~~~\textit{middle point of 2 points } \\\\ (\stackrel{x_1}{11}~,~\stackrel{y_1}{-3})\qquad (\stackrel{x_2}{x}~,~\stackrel{y_2}{y}) \qquad \left(\cfrac{ x_2 + x_1}{2}~~~ ,~~~ \cfrac{ y_2 + y_1}{2} \right) \\\\\\ \left(\cfrac{ x +11}{2}~~~ ,~~~ \cfrac{ y -3}{2} \right)~~ = ~~\stackrel{\stackrel{midpoint}{\downarrow }}{(7~~,~~-2}) \\\\[-0.35em] ~\dotfill$

$\cfrac{ x +11}{2}~~ = ~~7\implies x+11=14\implies \boxed{x=3} \\\\[-0.35em] ~\dotfill\\\\ \cfrac{ y -3}{2}~~ = ~~-2\implies y-3=-4\implies y=-1\implies y=-1i\implies \boxed{y=-i}$