# S Chand ICSE Mathematics Class 9 Solution Seventh Chapter Logarithm Exercise 7C (O.P. Malhotra, S.K. Gupta, Anubhuti Gangal)

### 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 113

(9) log (2 and 1/3)5

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

(11) Given log10 25 = x, log10 75 = y, evaluate without using logarithmic tables, in terms x, y

(i) log103

(ii) log102

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

(i) log (31.87)2

(ii) log10 0.03187

(iii) log10 √31870

(13) Solve the equation:

(i) log10 (x + 1) + log10 (x – 1) = log10 11 + 2 log103

(ii) log (10x + 5) – log (x – 4) = 2

Solution:       (28) If x2 + y2 = 51xy, prove that

Log x – y / 7 = ½ (log x + log y)

Solution: Updated: November 21, 2019 — 12:10 pm

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