AQA C1 2006 January — Question 8

Exam BoardAQA
ModuleC1 (Core Mathematics 1)
Year2006
SessionJanuary
TopicArea Under & Between Curves

8 The diagram shows the curve with equation \(y = 3 x ^ { 2 } - x ^ { 3 }\) and the line \(L\).
\includegraphics[max width=\textwidth, alt={}, center]{81f6fc30-982b-47b5-bab3-076cc0cc6563-5_479_816_406_596} 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 \(x = 2\).
  1. Find the area of the rectangle \(A B C D\).
    1. Find \(\int \left( 3 x ^ { 2 } - x ^ { 3 } \right) \mathrm { d } x\).
    2. Hence find the area of the shaded region bounded by the curve and the line \(L\).
  2. For the curve above with equation \(y = 3 x ^ { 2 } - x ^ { 3 }\) :
    1. find \(\frac { \mathrm { d } y } { \mathrm {~d} x }\);
    2. hence find an equation of the tangent at the point on the curve where \(x = 1\);
    3. show that \(y\) is decreasing when \(x ^ { 2 } - 2 x > 0\).
  3. Solve the inequality \(x ^ { 2 } - 2 x > 0\).