You can
put this solution on YOUR website! log4(4x) + 2·log4(x + 3) = 2
Get the left side to a single logarithm.
Use the rule
n·logBA = logBAn
to rewrite the second term:
log4(4x) + log4(x + 3)2 = 2
Use the rule:
logBA + logBC = logB(AC) to rewrite the
whole left side:
log4[4x(x + 3)2] = 2
Use the rule:
logBA = C can be rewritten as A = BC
to rewrite the equation:
4x(x + 3)2 = 42
4x(x + 3)(x + 3) = 16
4x(x2 + 3x + 3x + 9) = 16
4x(x2 + 6x + 9) = 16
To make things easier, divide both sides by 4
x(x2 + 6x + 9) = 4
x3 + 6x2 + 9x = 4
x3 + 4x2 + 9x - 4 = 0
There is no easy way to solve that by hand, so we
use a TI-82 or higher calculator and get
x = 0.3553013976
Edwin