5. (a) Given that \(t = \log _ { 3 } x\), find expressions in terms of \(t\) for
- \(\log _ { 3 } x ^ { 2 }\),
- \(\log _ { 9 } x\).
(b) Hence, or otherwise, find to 3 significant figures the value of \(x\) such that
$$\log _ { 3 } x ^ { 2 } - \log _ { 9 } x = 4 .$$