Monday 6 February 2017

LOGARITHMS 1H


Find x if Log2x + Log2(3x-4) =2

Solution

Log2x + Log2(3x-4) =2

Log2x(3x-4) =2

3x2-4x =22.

3x2-4x =4.

3x2-4x - 4=0

3x2+ 2x – 6x- 4=0       [Splitting -4x into 2x – 6x]

(3x2+ 2x) – (6x- 4)=0     [grouping the factors] 

x(3x+ 2) – 2(3x+ 2)=0     [taking out common factors]
 
(3x+ 2)(x-2)=0 
   
3x+ 2=0 OR x-2=0   
 
3x = -2 OR x = 2

3x = -2 OR x = 2
3      3

x = -2/3 OR x = 2

Hence x = -2/3 OR x = 2

TRY THIS…………………………  


Find x if Log25x + Log25(x-24) =1

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