**S Chand ICSE Mathematics Class 9 Solution Seventh Chapter Logarithm Exercise 7C**

**If log 2 = 0.3010, log 3 = 0.4771, log 5 = 0.6990, log 7 = 0.8451 and log 11 = 1.0414, find the following:**

**(1) log 6**

**(2) log 12**

**(3) log 15**

**(4) log 200**

**(5) log 36**

**(6) log 80**

**(7) log 2 and 1/3**

**(8) log 11 ^{3}**

**(9) log (2 and 1/3) ^{5}**

**Solution: **

**(10) I f log 6 = 0.7782, find the value of log 36.**

**(11) Given log _{10} 25 = x, log_{10} 75 = y, evaluate without using logarithmic tables, in terms x, y**

**(i) log _{10}3**

**(ii) log _{10}2**

**Solution: **

**(12) Given log 31.87 = x, write down in terms of x:**

**(i) log (31.87) ^{2}**

**(ii) log _{10} 0.03187**

**(iii) log _{10} √31870**

**(13) Solve the equation:**

**(i) log _{10} (x + 1) + log_{10} (x – 1) = log_{10} 11 + 2 log_{10}3**

**(ii) log (10x + 5) – log (x – 4) = 2**

**Solution: **

**(28) If x ^{2} + y^{2} = 51xy, prove that **

**Log x – y / 7 = ½ (log x + log y)**

**Solution: **

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