Limit of as
The limit of as is .
How to work it out
- 1
We want what x * ln(x) approaches as x → 0⁺.
- 2
Direct substitution gives an indeterminate form: 0·∞. It does not tell us the limit.
- 3
L'Hôpital's rule: when the form is 0·∞, the limit equals the limit of the ratio of the derivatives.
- 4
Still 0·∞ (both vanish again), so apply it once more.
- 5
Still 0·∞ (both vanish again), so apply it once more.
- 6
Method: rewrite as ln x / (1/x) and use L'Hôpital: the logarithm grows slower than any power.
- 7
Result:
LaTeX source of the formulas on this page
\[ \lim_{x \to 0^{+}} x \ln\left(x\right) = 0 \]
\[ \lim_{x \to 0^{+}} x \ln\left(x\right) \]
\[ \lim \frac{\ln\left(x\right)}{\frac{1}{x}} = \lim \frac{\frac{1}{x}}{\frac{-1}{x^{2}}} \]
\[ \lim \frac{\frac{1}{x}}{\frac{-1}{x^{2}}} = \lim \frac{\frac{-1}{x^{2}}}{\frac{-\left(\left(-2\right) x\right)}{\left(x^{2}\right)^{2}}} \]
\[ \lim \frac{\frac{-1}{x^{2}}}{\frac{-\left(\left(-2\right) x\right)}{\left(x^{2}\right)^{2}}} = \lim \frac{\frac{-\left(\left(-2\right) x\right)}{\left(x^{2}\right)^{2}}}{\frac{2 \left(x^{2}\right)^{2} - -\left(\left(-2\right) x 2 x^{2} 2 x\right)}{\left(\left(x^{2}\right)^{2}\right)^{2}}} \]Values of x * ln(x) as x → 0⁺ (computed)
| x | f(x) | Distance from the limit |
|---|---|---|
| 0.1 | -0.23025851 | 2.30e-1 |
| 0.01 | -0.046051702 | 4.61e-2 |
| 0.001 | -0.0069077553 | 6.91e-3 |
| 0.0001 | -0.00092103404 | 9.21e-4 |
| 0.00001 | -0.00011512925 | 1.15e-4 |
Questions
What is the limit of x * ln(x) as x approaches 0⁺?
The limit of as is .
Which form is it?
0·∞.