LOGARITHMS 16

If Log(30x-90/5+x) = 1. Find x.

Solution

Log(30x-90/5+x) = 1.

Log₁₀(30x-90/5+x) = 1.

 30x-90 = 10¹. After changing into exponential form

   5+x

30x-90 = 10    since [10¹=10]

   5+x

30x-90 = 10(5+x)    after cross multiply

  

30x-90 = 50+10x

30x-10x = 50+90 [collecting like terms]

20x = 140

x=7  [after dividing by 20 both sides]

Hence x=7.

TRY THIS……………

Log(30x-120/3+x) = 1.