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Home > A2C > Chapter 11 > Lesson 11.2.3 > Problem 11-77

11-77.
  1. Use the properties of logarithms to rewrite each equation and then solve. Check for extraneous roots. Homework Help ✎

    1. log(x) + log(x + 21) = 2

    2. 2log4(x) − log4(3) = 2

    3. log2(9x + 5) − log2(x2 − 1) = 2

    4. log7(x + 1) + log7(x − 5) = 1

log(x2 + 21x) = 2

x2 + 21x = 102

(x − 4)(x + 25) = 0

4

3

See parts (a) and (b).