Question

The midpoint of AB is M(6, 3) . If the coordinates of A are (7, 4) , what are the coordinates of B?

Answer 1

`~~~~~~~~~~~~\textit{middle point of 2 points } \\\\ A(\stackrel{x_1}{7}~,~\stackrel{y_1}{4})\qquad B(\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 +7}{2}~~~ ,~~~ \cfrac{ y +4}{2} \right) ~~ = ~~\stackrel{\textit{\LARGE M}}{(6~~,~~3)} \\\\[-0.35em] ~\dotfill\\\\ \cfrac{ x +7}{2}=6\implies x+7=12\implies \boxed{x=5} \\\\[-0.35em] ~\dotfill\\\\ \cfrac{ y +4}{2}=3\implies y+4=6\implies \boxed{y=2}`