LOGARITHMS J5

 If log_x81 – log₂2048 = -7; find x

 

Solution

 

log_x81 – log₂2048 = -7

 

log_x81 – log₂2¹¹ = -7   [SINCE 2048 = 2 power  11]

 

log_x81 – 11log₂2 = -7

 

log_x81 – (11 x 1) = -7

 

log_x81 – 11 = -7

 

log_x81 = -7 + 11

 

log_x81 = 4

 

81 = x⁴

 

3⁴ = x⁴      [equal Powers cancel out]

 

x = 3

 

Hence x = 3.

 

TRY THIS..............

 

 If log_x243 – log₅3125 = 0; find x