LOGARITHMS 9

Log₄7x – Log₄(x+3)-Log₄5=0.

Solution

Log₄7x – Log₄(x+3)-Log₄5=0.

Log₄4x – [ Log₄(x+7) + Log₄5]=0.

Log₄{4x/(x+7)5} =0.

4x            =   4⁰   = 1

5(x+7)

4x          = 1

5x+35

5x + 35 = 4x

5x - 4x + 35 = 0

5x - 4x = - 35

x = -35

Hence x=-35

TRY THIS……………………….. 

NECTA 2011,  QN 2a

Log₄5x – Log₄(x+2) - Log₄3 = 0.