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Limit Calculator

Read asf(x)=x2−1x−1f(x) = \frac{x^{2} - 1}{x - 1}

Powers ^ · multiply with * or a space · sqrt( ) ln( ) log( ) sin( ) cos( ) tan( ) e pi |x| · implicit products like 2x or x sin x work

A number, pi, e, inf or -inf

Direction

Try an example

Limit

lim⁡x→1x2−1x−1=2\lim_{x \to 1} \frac{x^{2} - 1}{x - 1} = 2

How it was found

Direct substitution does not work here (it gives an undefined or indeterminate value such as 0/0), so the limit is estimated from f(x) at points closer and closer to the target, then extrapolated. Values that match a simple exact number (a fraction, π, e, √2) to about 7 digits are shown in exact form.

L'Hôpital's rule confirms it (0/0 form)

lim⁡x→1f(x)=lim⁡x→12 x1=2\lim_{x \to 1} f(x) = \lim_{x \to 1} \frac{2\,x}{1} = 2
From the left
xf(x)
0.91.9
0.991.99
0.9991.999
0.99991.9999
0.999991.99999
0.9999991.999999
From the right
xf(x)
1.12.1
1.012.01
1.0012.001
1.00012.0001
1.000012.00001
1.0000012.000001

Graph

-2-101234-1012345
f(x)

Evaluate the limit of a function as x approaches a number or ±∞, from both sides or from one. The calculator tries direct substitution, recognizes indeterminate forms such as 0/0, confirms them with L'Hôpital's rule where it can, and shows f(x) closing in from each side.

Formula

lim⁡x→af(x)=L\lim_{\text{x} \to \text{a}} \text{f}(\text{x}) = \text{L}
if f(a)/g(a)=00or∞/∞:lim⁡x→af(x)/g(x)=lim⁡x→af′(x)/g′(x)\text{if f}(\text{a})/\text{g}(\text{a}) = \frac{0}{0} \text{or} \infty / \infty : \lim_{\text{x} \to \text{a}} \text{f}(\text{x})/\text{g}(\text{x}) = \lim_{\text{x} \to \text{a}} \text{f}'(\text{x})/\text{g}'(\text{x})

Worked Example

f(x)sin x / x
x approaches0
Result: 1

Substituting x = 0 gives 0/0, an indeterminate form. L'Hôpital's rule replaces the quotient with cos x ÷ 1, which equals 1 at x = 0, and the table agrees: f(0.001) = 0.99999983 from both sides.

Frequently Asked Questions

What is an indeterminate form?

A result like 0/0, ∞/∞, 0·∞, ∞ − ∞, 1^∞, 0⁰ or ∞⁰ that substitution can't settle, because the answer depends on how fast each part approaches its value. (x² − 1)/(x − 1) gives 0/0 at x = 1 but simplifies to x + 1, so its limit is 2.

When does a limit not exist?

When the left- and right-hand limits differ (a jump), when the function grows without bound in different directions (1/x at 0 goes to −∞ from the left and +∞ from the right), or when it oscillates forever, like sin(1/x) near 0.

What is the limit of (1 + 1/x)^x as x goes to infinity?

e ≈ 2.71828. It is a 1^∞ form: taking the logarithm gives x · ln(1 + 1/x), which tends to 1, so the limit is e¹.