# Introduction to Limits

## Key Questions

• A limit allows us to examine the tendency of a function around a given point even when the function is not defined at the point. Let us look at the function below.
$f \left(x\right) = \frac{{x}^{2} - 1}{x - 1}$
Since its denominator is zero when $x = 1$, $f \left(1\right)$ is undefined; however, its limit at $x = 1$ exists and indicates that the function value approaches $2$ there.
lim_{x to 1}{x^2-1}/{x-1} =lim_{x to 1}{(x+1)(x-1)}/{x-1} =lim_{x to 1}(x+1)=2

This tool is very useful in calculus when the slope of a tangent line is approximated by the slopes of secant lines with nearing intersection points, which motivates the definition of the derivative.

• A limit allows us to examine the tendency of a function around a given point even when the function is not defined at the point. Let us look at the function below.
$f \left(x\right) = \frac{{x}^{2} - 1}{x - 1}$
Since its denominator is zero when $x = 1$, $f \left(1\right)$ is undefined; however, its limit at $x = 1$ exists and indicates that the function value approaches $2$ there.
lim_{x to 1}{x^2-1}/{x-1} =lim_{x to 1}{(x+1)(x-1)}/{x-1} =lim_{x to 1}(x+1)=2

This tool is very useful in calculus when the slope of a tangent line is approximated by the slopes of secant lines with nearing intersection points, which motivates the definition of the derivative.