Answer:
[tex]y=\frac{1}{2}x -1[/tex]
Step-by-step explanation:
Perpendicular lines have slopes which are negative reciprocals of each other. The slope of the line y=-2x-1 is -2. The slope perpendicular to it is 1/2.
Using m=1/2, substitute it and (2,1) into the point slope form and simplify to find the y-intercept.
[tex]y-y_1 = m(x-x_1)\\y-1=\frac{1}{2}(x-2)\\y-1=\frac{1}{2}(x-4)\\y-1=\frac{1}{2}x-2\\y=\frac{1}{2}x-1[/tex]