Fig. 8 shows a right-angled triangle with base \(2x + 1\), height \(h\) and hypotenuse \(3x\).
\includegraphics{figure_1}
- Show that \(h^2 = 5x^2 - 4x - 1\). [2]
- Given that \(h = \sqrt{7}\), find the value of \(x\), giving your answer in surd form. [3]