Tangent Line Equation Calculator

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A step by step tangent line equation calculator is presented.

Equation of the Tangent Line

Let \( f(x) \) be a function. The slope \( m \) of the tangent line to the graph of \( f(x) \) at the point of tangency \( (x_0 , f(x_0)) \) is given by:
\[ m = f'(x_0) \]
where \( f'(x_0) \) is the first derivative of \( f(x) \) evaluated to \( x = x_0 \)
The equation of the tangent to the graph of \( f(x) \) at \( x = x_0\) in point slope form is given by
\( y - f(x_0) = m(x - x_0) \)
and in slope intercept form is given by
\( y = m x + f(x_0) - m x_0 \)
You enter \( f(x) \) and \( x_0 \) and the calculator displays the point of tangency \( ( x_0 , f(x_0) ) \), the slope \( m \) and the equation of the line in slope intercept form \( y = m x + b \) with the y intercept \( b = f(x_0) - m x_0 \).


Use of the Tangent Line Calculator

1 - Enter and edit function $f(x)$ and click "Enter Function" then check what you have entered. Enter \( x_0 \)
Note that the five operators used are: + (plus) , - (minus), / (division) , ^ (power) and * (multiplication). (example: f(x) = x^3 + 1/x.(more notes on editing functions are located below)
2 - Click "Calculate Equations".
3 - Note that the natural logarirthm is entered as \( log(x) \), the natural exponential as   \( exp(x) \).
4 - Note that a function \( f(x) \) to some power \(n\) is entered as: \( (f(x))^n \). Example:   \( sin^2(2x-1) \)   is entered as   (sin(2x-1))^2.
5 - Note Enter decimal numbers as fractions between brackets. Example : enter (1/2) instead of 0.5


$f(x)$ =


$x_0$ =


Number of Decimals =






Notes: In editing functions, use the following:
1 - The five operators used are: + (plus) , - (minus), / (division) , ^ (power) and * (multiplication). (example:    f(x) = x^2 + 1/x + log(x)  )
2 - The function square root function is written as (sqrt). (example: sqrt(x^2-1) for \( \sqrt {x^2 - 1} \) )
3 - The exponential function is written as exp(x). (Example: exp(x+2)    for    \( e^{x+2} \) )
4 - The log base e function is written as log(x). (Example: log(x^2-2)    for    \( \ln(x^2 - 2 \) )
Here are some examples of functions that you may copy and paste to practice:
x^2 + x +2       sin(x) + cos(x)       1/(x-2)       x^2+log(2*x + 2)      (x+2)^2(x^2+1)-1
2*sin(2x^2+2x-1)       exp(2x^2)       tan(x)       (x-1)/(x+3)^3



More References and Links

Tangent Line
derivative
rules
formulas