If the points (4,2) and )-1, k) are on a line that is perpendicular to the line y=2x+1, what is the value of k?

Answer 1

the slope of the given line is 2 ... y = m x + b , m is the slope

perpendicular lines have negative-reciprocal slopes
... so the new line slope is -1/2

(2 - k) / (4 - -1) = -1/2 ... solve for k