take the derivative of a function in php

main.php
// Define your function as a string
$function = "x^2 + 3x + 2";

// Convert the string to a function
$function = create_function('$x', "return {$function};");

// Define a small number for numerical calculations
$h = 0.0001;

// Define a point at which to take the derivative
$x = 5;

// Use numerical methods to find the derivative
$derivative = ($function($x + $h) - $function($x)) / $h;

// Output the result
echo "The derivative of f(x) = {$function} at x = {$x} is {$derivative}"; 
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main.php
The derivative of f(x) = x^2 + 3x + 2 at x = 5 is 13.000100000066
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