Use the rules of logs.
log(a) + log(b) = log(ab)
log(x) + log(x-3) = log(x*(x-3)) = log(5x)
So x*(x-3) = 5x. Solve that for x.
log(a) + log(b) = log(ab)
log(x) + log(x-3) = log(x*(x-3)) = log(5x)
So x*(x-3) = 5x. Solve that for x.
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Hello,
Simplicity itself: you just have to remember two things:
▪ Logarithmic functions are only defined for positive values.
▪ Considering two positive reals a and b, log(a) + log(b) = log(ab)
Hence
log(x) + log(x - 3) = log (5x)
log[x(x - 3)] = log(5x)
x(x - 3) = 5x
x² - 3x - 5x = 0
x(x - 8) = 0
So either x=0 or x=8.
Since logarithmic functions are only defined for positive values, x=0 is unvalid and:
x = 8
Logically,
Dragon.Jade :-)
Simplicity itself: you just have to remember two things:
▪ Logarithmic functions are only defined for positive values.
▪ Considering two positive reals a and b, log(a) + log(b) = log(ab)
Hence
log(x) + log(x - 3) = log (5x)
log[x(x - 3)] = log(5x)
x(x - 3) = 5x
x² - 3x - 5x = 0
x(x - 8) = 0
So either x=0 or x=8.
Since logarithmic functions are only defined for positive values, x=0 is unvalid and:
x = 8
Logically,
Dragon.Jade :-)