\includegraphics{figure_2}
Figure 2 shows part of the curve \(C\) with equation
$$y = 9 - 2x - \frac{2}{\sqrt{x}}, \quad x > 0.$$
The point \(A(1, 5)\) lies on \(C\) and the curve crosses the \(x\)-axis at \(B(b, 0)\), where \(b\) is a constant and \(b > 0\).
- Verify that \(b = 4\). [1]
The tangent to \(C\) at the point \(A\) cuts the \(x\)-axis at the point \(D\), as shown in Fig. 2.
- Show that an equation of the tangent to \(C\) at \(A\) is \(y + x = 6\). [4]
- Find the coordinates of the point \(D\). [1]
The shaded region \(R\), shown in Fig. 2, is bounded by \(C\), the line \(AD\) and the \(x\)-axis.
- Use integration to find the area of \(R\). [6]