The line MN is shown on the grid.
Find the equation of the perpendicular bisector of line MN.

Find midpoint coordinates:
[tex]\rightarrow \sf (\dfrac{-1+3}{2} ), \ (\dfrac{7+(-1)}{2} )[/tex]
[tex]\hookrightarrow \sf (1, \ 3)[/tex]
Find the gradient of MN:
[tex]\dashrightarrow \sf \dfrac{-1-7}{3-(-1)}[/tex]
[tex]\dashrightarrow \sf -2[/tex]
slope of perpendicular bisector:
[tex]\rightarrow \sf \dfrac{1}{2}[/tex]
Equation:
[tex]\sf \rightarrow y = \dfrac{1}{2}x+\dfrac{5}{2}[/tex]
Answer:
[tex]y=\dfrac12x+\dfrac52[/tex]
Step-by-step explanation:
M = (-1, 7)
N = (3, -1)
[tex]\sf slope\:of\:MN=\dfrac{y_n-y_m}{x_n-x_m}= \dfrac{-1-7}{3-(-1)}=-2[/tex]
If two lines are perpendicular to each other, the product of their slopes will be -1. Therefore, the slope (m) of the line perpendicular to MN is:
[tex]\sf \implies -2 \times m=-1[/tex]
[tex]\sf \implies m=\dfrac12[/tex]
If the line bisects the line MN, it will intersect it at the midpoint of MN:
[tex]\begin{aligned}\textsf{Midpoint of MN} & =\left(\dfrac{x_m+x_n}{2},\dfrac{y_m+y_n}{2}\right)\\ & =\left(\dfrac{-1+3}{2},\dfrac{7+(-1)}{2}\right)\\ & =(1,3)\end{aligned}[/tex]
Finally, use the point-slope form of the linear equation with the found slope and the midpoint of MN:
[tex]y-y_1=m(x-x_1)[/tex]
[tex]\implies y-3=\dfrac12(x-1)[/tex]
[tex]\implies y=\dfrac12x+\dfrac52[/tex]