well you would start at x=100 as 1/100 is apporximately 1/98
so find the tangent line at x=100
y= 1/x , dy/dx= -1/ ( 2sqrtx)
when x=100, dy/dx= m= -1/20
when x=100, y=1/100
y-y1=m(x-x1)
etc, then you would set x=98 and solve for y..... tell me if this helps
