(2) The slope of 4x - ky = 6 can be calculated by re-expressing it in slope-intercept form:

`y=4/kx-6/k`

So we see the slope is `4/k`.

The slope of `6x + 3y + 2 = 0` can also be calculated by re-expressing it in slope-intercept form:

`y=(-6)/3x-2/3=-2x-2/3`

So we see the slope is `-2`.

For the lines to be perpendicular, we need

`4/kxx-2=-1`

This gives `k = 8`.