Hello I have the question 'Find the equations of the tangents to these curves at correspnding points '

I'm getting very frustrated becuase I cannot where I'm going wrong (Headbang). Heres how i've been doing it.

y=2/x² , x=2 hence points (2,1/2)

y=2x-² (Is this where I went wrong?)

y=-4x^-3

dy/dx = 4*1/8

=1/2

y-1/2=4/8(x-2)

y=1/2x-1/2

Yet this isnt the line equation :(