A line passing through (2, –1) and (–1, y) is perpendicular to a line with slope -2. Find the value of y?

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A line passing through (2, –1) and (–1, y) is perpendicular to a line with slope -2. Find the value of y?

A line passing through (2, –1) and (–1, y) is perpendicular to a line with slope -2. Find the value of y

Thanks in advance for any help you can give.

perpendicular lines have negative inverse slopes. mm' = -1

So slope 1/2 is perpendicular to slope -2.

but slope = change in y/change in x

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

-3/2 = y+1

y = -3/2 -1 = -5/2