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Express in Terms of Log 2 and Log 3 : "Log"75/51 - 2"Log"5/9 + "Log"32/243 - Mathematics

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Question

Express in terms of log 2 and log 3 :
`"log"75/16 - 2"log"5/9 + "log"32/243`

Sum

Solution

`"log"75/16 - 2"log"5/9 + "log"32/243`

= `"log"75/16 - "log"(5/9)^2 + "log"32/243`

= `"log"75/16 - "log"( 5/9 xx 5/9 ) + "log"32/243`

= `"log"75/16 - "log"25/81 + "log"32/243`

= `"log"((75/16)/(25/81))       .....[ log_am - log_an = log_a(m/n)]`

= `"log"(75/16) xx (81/25) + log(32/243)`

= `"log"( 3 xx 25)/16 xx 81/25 + "log"32/243`

= `"log"243/16 + "log"32/243`

= `"log"( 243/16 xx 32/243 )`     .....[logam + logan = logamn]

= `"log"32/16`
= log 2

shaalaa.com
Laws of Logarithm
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Chapter 8: Logarithms - Exercise 8 (B) [Page 106]

APPEARS IN

Selina Concise Mathematics [English] Class 9 ICSE
Chapter 8 Logarithms
Exercise 8 (B) | Q 1.5 | Page 106
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