What is the integral of x/((1-x)) ?

The integral of x/((1-x)) is 1-x-ln|1-x|+C

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integral of x/((1-x))

\int \frac{x}{( 1 - x )} d x

1 - x - ln ∣ 1 - x ∣ + C

Solution steps

\int \frac{x}{1 - x} d x

Apply u-substitution

= \int - \frac{- u + 1}{u} d u

Take the constant out:

\int a \cdot f (x) d x = a \cdot \int f (x) d x

= - \int \frac{- u + 1}{u} d u

Expand

\frac{- u + 1}{u} : - 1 + \frac{1}{u}

= - \int - 1 + \frac{1}{u} d u

Apply the Sum Rule:

\int f (x) \pm g (x) d x = \int f (x) d x \pm \int g (x) d x

= - (- \int 1 d u + \int \frac{1}{u} d u)

\int 1 d u = u

\int \frac{1}{u} d u = ln ∣ u ∣

= - (- u + ln ∣ u ∣)

Substitute back

u = 1 - x

= - (- (1 - x) + ln ∣ 1 - x ∣)

Simplify

= 1 - x - ln ∣ 1 - x ∣

Add a constant to the solution

= 1 - x - ln ∣ 1 - x ∣ + C