Hello, slaypullingcat!
The procedure is simple, but there's a LOT of algebra!
I was lucky to get the answer on the first try . . .
Show that the tangent to: . with gradient
. . has y-intercept: .
The derivative of: . [1] .is: .
If the gradient is
Substitute into [1]: .
The tangent has point . and slope
Its equation is: .
. .