Find \(\frac { \mathrm { d } y } { \mathrm {~d} x }\).
Find, in exact form, the range of values of \(x\) for which \(x ^ { 3 } - 6 x + 2\) is a decreasing function.
Find the equation of the tangent to the curve at the point \(( - 1,7 )\).
Find also the coordinates of the point where this tangent crosses the curve again.