7 [Figure 1, printed on the insert, is provided for use in this question.]
The diagram shows the curve
$$y = x ^ { 3 } - x + 1$$
The points \(A\) and \(B\) on the curve have \(x\)-coordinates - 1 and \(- 1 + h\) respectively.
\includegraphics[max width=\textwidth, alt={}, center]{a0a30197-ca11-40d9-9ccd-30281c5e0fb4-05_978_1184_676_411}
- Show that the \(y\)-coordinate of the point \(B\) is
$$1 + 2 h - 3 h ^ { 2 } + h ^ { 3 }$$
- Find the gradient of the chord \(A B\) in the form
$$p + q h + r h ^ { 2 }$$
where \(p , q\) and \(r\) are integers.
- Explain how your answer to part (a)(ii) can be used to find the gradient of the tangent to the curve at \(A\). State the value of this gradient.
- The equation \(x ^ { 3 } - x + 1 = 0\) has one real root, \(\alpha\).
- Taking \(x _ { 1 } = - 1\) as a first approximation to \(\alpha\), use the Newton-Raphson method to find a second approximation, \(x _ { 2 }\), to \(\alpha\).
- On Figure 1, draw a straight line to illustrate the Newton-Raphson method as used in part (b)(i). Show the points \(\left( x _ { 2 } , 0 \right)\) and \(( \alpha , 0 )\) on your diagram.