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Limit of 2xβˆ’1x\frac{2^{x} - 1}{x} as xβ†’0x \to 0

The limit of 2xβˆ’1x\frac{2^{x} - 1}{x} as xβ†’0x \to 0 is ln⁑2\ln 2.

Graph of (2^x - 1) / x near x = 0-1.5-1-0.50.511.50.40.60.811.2limit = ln 2 β‰ˆ 0.69314718f(x)
Graph of (2^x - 1) / x near x = 0. The open circle marks the point x = 0, where the function may be undefined; the curve still heads to ln 2 β‰ˆ 0.69314718.

How to work it out

  1. 1

    We want what (2x2^{x} - 1) / x approaches as x β†’ 0.

    lim⁑xβ†’02xβˆ’1x\lim_{x \to 0} \frac{2^{x} - 1}{x}
  2. 2

    Direct substitution gives an indeterminate form: 0/0. It does not tell us the limit.

  3. 3

    L'HΓ΄pital's rule: when the form is 0/0, the limit equals the limit of the ratio of the derivatives.

    lim⁑2xβˆ’1x=lim⁑2xln⁑(2)1\lim \frac{2^{x} - 1}{x} = \lim \frac{2^{x} \ln\left(2\right)}{1}
  4. 4

    Now substitute x = 0: the denominator is not 0 any more.

    0.693147181=0.69314718\frac{0.69314718}{1} = 0.69314718
  5. 5

    Method: the derivative of 2x2^{x} at 0 is ln 2.

  6. 6

    Result:

    lim⁑xβ†’02xβˆ’1x=ln⁑2\lim_{x \to 0} \frac{2^{x} - 1}{x} = \ln 2
LaTeX source of the formulas on this page
\[ \lim_{x \to 0} \frac{2^{x} - 1}{x} = \ln 2 \]
\[ \lim_{x \to 0} \frac{2^{x} - 1}{x} \]
\[ \lim \frac{2^{x} - 1}{x} = \lim \frac{2^{x} \ln\left(2\right)}{1} \]
\[ \frac{0.69314718}{1} = 0.69314718 \]

Values of (2x2^{x} - 1) / x as x β†’ 0 (computed)

xf(x)Distance from the limit
0.10.717734632.46e-2
-0.10.669670082.35e-2
0.010.695555012.41e-3
-0.010.690750462.40e-3
0.0010.693387462.40e-4
-0.0010.692907012.40e-4
0.00010.693171202.40e-5
-0.00010.693123162.40e-5
0.000010.693149582.40e-6
-0.000010.693144782.40e-6

Questions

What is the limit of (2x2^{x} - 1) / x as x approaches 0?

The limit of 2xβˆ’1x\frac{2^{x} - 1}{x} as xβ†’0x \to 0 is ln⁑2\ln 2.

Which form is it?

0/0.

More well-known limits

    Limit of (2^x - 1) / x as x β†’ 0: ln 2 β‰ˆ 0.69314718 | WordGPT