Simplify ln(xx1)+ln(x+1x)ln(x21) ?

2 Answers
Apr 9, 2017

2log(x1)

Explanation:

Using the logarithmic properties

log(ab)=loga+logb
logab=bloga

we have

log(xx1)+log(x+1x)log(x21)=log(xx1)(x+1x)x21

=log(x+1x1(x+1)(x1))=log(1(x1)2)=log((x1)2)=2log(x1)

Apr 9, 2017

Given: ln(xx1)+ln(x+1x)ln(x21)

Addition of logarithms is the same as multiplication of their arguments:

ln(xx1x+1x)ln(x21)

Simplify a bit:

ln(x+1x1)ln(x21)

Subtractions of logarithms is the same as division of their arguments:

ln(x+1(x1)(x21))

Factor the quadratic:

ln(x+1(x1)(x1)(x+1))

Cancel the common factor x+1:

ln(1(x1)(x1))

Write the denominator as a square:

ln(1(x1)2)

Because 1=12, we can write it this way:

ln((1x1)2)

Use the property ln(ac)=(c)ln(a) to bring the -2 outside:

2ln(x1)