8 The diagram shows the curve with equation \(y = 3 x ^ { 2 } - x ^ { 3 }\) and the line \(L\).
\includegraphics[max width=\textwidth, alt={}, center]{b83c4e3a-36a6-4ca9-b44f-489676ca86d4-06_469_802_411_603}
The points \(A\) and \(B\) have coordinates \(( - 1,0 )\) and \(( 2,0 )\) respectively. The curve touches the \(x\)-axis at the origin \(O\) and crosses the \(x\)-axis at the point \(( 3,0 )\). The line \(L\) cuts the curve at the point \(D\) where \(x = - 1\) and touches the curve at \(C\) where \(x = 2\).
- Find the area of the rectangle \(A B C D\).
- Find \(\int \left( 3 x ^ { 2 } - x ^ { 3 } \right) \mathrm { d } x\).
- Hence find the area of the shaded region bounded by the curve and the line \(L\).
- For the curve above with equation \(y = 3 x ^ { 2 } - x ^ { 3 }\) :
- find \(\frac { \mathrm { d } y } { \mathrm {~d} x }\);
- hence find an equation of the tangent at the point on the curve where \(x = 1\);
- show that \(y\) is decreasing when \(x ^ { 2 } - 2 x > 0\).
- Solve the inequality \(x ^ { 2 } - 2 x > 0\).