3log5=a dan 3log7=b, nilai 45log(akar63)?

ingat bahwa :
[tex] log_{a}(b) = \frac{ log_{c}(b) }{ log_{c}(a) } [/tex]
kita ambil c = 3, sehingga :
[tex] log_{45}( \sqrt{63} ) = \frac{ log_{3}( {(63)}^{ \frac{1}{2} } ) }{ log_{3}(45) } \\ = \frac{ \frac{1}{2} log_{3}( {3}^{2} \times 7) }{ log_{3}( {3}^{2} \times 5 ) } \\ = \frac{ \frac{1}{2}(2 log_{3}(3) + log_{3}(7) ) }{2 log_{3}(3) + log_{3}(5) } \\ = \frac{ \frac{1}{2} (2 + log_{3}(7)) }{2 + log_{3}(5) } \\ = \frac{1 + \frac{1}{2} log_{3}(7) }{2 + log_{3}(5) } [/tex]
jadikan variabel :
[tex] \frac{1 + \frac{1}{2} b}{2 + a} \\ = \frac{b + 2}{4 + 2a} [/tex]