# cal

posted by
**Melba** on
.

Equations of the tangent lines to hyperbola xy=1 that pass through point (-1,1)

I know the graph of y=1/x but not sure about the tangent lines at given point. Are the lines tangent to (1,1) and (-1,-1)?

You're correct, the graph is y=1/x, so find y' to get the slope at any point on the graph (except the origin). I only found one tangent line through (-1,1), I'm not sure what other point the question has in mind.