| Exam Board | Edexcel |
| Module | AEA (Advanced Extension Award) |
| Year | 2012 |
| Session | June |
| Topic | Laws of Logarithms |
5.[In this question the values of \(a , x\) ,and \(n\) are such that \(a\) and \(x\) are positive real numbers,with \(a > 1 , x \neq a , x \neq 1\) and \(n\) is an integer with \(n > 1\) ]
Sam was confused about the rules of logarithms and thought that
$$\log _ { a } x ^ { n } = \left( \log _ { a } x \right) ^ { n }$$
(a)Given that \(x\) satisfies statement(1)find \(x\) in terms of \(a\) and \(n\) .
Sam also thought that
$$\log _ { a } x + \log _ { a } x ^ { 2 } + \ldots + \log _ { a } x ^ { n } = \log _ { a } x + \left( \log _ { a } x \right) ^ { 2 } + \ldots + \left( \log _ { a } x \right) ^ { n }$$
(b)For \(n = 3 , x _ { 1 }\) and \(x _ { 2 } \left( x _ { 1 } > x _ { 2 } \right)\) are the two values of \(x\) that satisfy statement(2).
(i)Find,in terms of \(a\) ,an expression for \(x _ { 1 }\) and an expression for \(x _ { 2 }\) .
(ii)Find the exact value of \(\log _ { a } \left( \frac { x _ { 1 } } { x _ { 2 } } \right)\) .
(c)Show that if \(\log _ { a } x\) satisfies statement(2)then
$$2 \left( \log _ { a } x \right) ^ { n } - n ( n + 1 ) \log _ { a } x + \left( n ^ { 2 } + n - 2 \right) = 0$$