Question

Find the equation of the perpendicular bisector of the line segment joining the points (1, 2) and (-2, 1)

Does it mean I have to find the line. Then find a line that cuts that line in to half because perpendicular bisector

Answer 1

just find the slope of the line: 1/3

the perp has slope -3, so now we have a midpoint (-1/2,3/2) and a slope (-3), and our line is

y - 3/2 = -3(x + 1/2)

Answer 2

So the equation is -3(x+1/2)?
Like there's no Y= in it?

Answer 3

I gave you the equation. There's always a y. If you want it it slope-intercept form, which most people find comforting, that would be

y = -3x

Visit

http://rechneronline.de/function-graphs/

and plot the two functions

(x+5)/3 and -3x

and you will see that the two lines intersect midway between the two given points