Question 106

# Find the value of x which satisfies the following equation $$4log_7 (x - 8) = log_3 81$$

Solution

$$4log_7 (x - 8) = log_3 81$$

$$4log_7 (x - 8) = log_3 3^{4}$$

$$4log_7 (x - 8) =4*log_3 3$$

$$log_7 (x - 8) =1$$

$$(x - 8) =7^{1}$$

$$x = 7+8$$

$$x = 15$$