Here's the question again

How do I find all line through (6, -1) for which the product of x- & y- intercepts is 3?

Thanks again

The equation would have the form

(y+1) = m (x-6),

where m is the slope. It can be rewritten
y = mx -6m -1

The y intercept is at y = -6m -1.
The x intercept is at x = 6 + 1/m

Require that (-6m -1)*(6 + 1/m) = 3, and solve for m.