5. (a) Given that \(t = \log _ { 3 } x\),
- write down an expression in terms of \(t\) for \(\log _ { 3 } x ^ { 2 }\),
- show that \(\log _ { 9 } x = \frac { 1 } { 2 } t\).
(b) Hence, or otherwise, find to 3 significant figures the value of \(x\) such that
$$\log _ { 3 } x ^ { 2 } - \log _ { 9 } x = 4$$