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

11-77.

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

log(

*x*) + log(*x*+ 21) = 22log

_{4}(*x*) − log_{4}(3) = 2log

_{2}(9*x*+ 5) − log_{2}(*x*^{2}− 1) = 2log

_{7}(*x*+ 1) + log_{7}(*x*− 5) = 1

log(*x*^{2} + 21*x*) = 2

*x*^{2} + 21*x* = 10^{2}

(*x* − 4)(*x* + 25) = 0

4

3

See parts (a) and (b).