d/dx Derivative Calculator
Find the derivative of any polynomial. Enter the coefficients from the highest degree to the constant term and get the differentiated result instantly with each step shown.
What is this tool?
The derivative measures how a function changes as its input changes. It is one of the most powerful concepts in mathematics, capturing the idea of instantaneous rate of change. The derivative of a position function gives velocity; the derivative of velocity gives acceleration; the derivative of a cost function gives the marginal cost. In machine learning, derivatives drive gradient descent; in physics, they describe motion and change; in economics, they model marginal effects.
For polynomials, differentiation follows the power rule: d/dx [xⁿ] = n·xⁿ⁻¹. Each term is differentiated independently. For example, d/dx [3x³ + 2x² + 5x + 7] = 9x² + 4x + 5. The constant term always differentiates to zero because a constant does not change. The linear term cx becomes simply c (since cx¹ differentiates to 1·cx⁰ = c).
This derivative calculator handles polynomials of any degree. You enter the coefficients from the highest power of x down to the constant term, and it applies the power rule to each term, showing the complete derivative. All computation happens locally in your browser.How it works
The power rule for differentiation states that for any term c·xⁿ (where n > 0), the derivative is c·n·xⁿ⁻¹. The calculator processes each coefficient in order. If you enter coefficients [a, b, c, d] representing ax³ + bx² + cx + d, the result is 3a·x² + 2b·x + c. The constant d differentiates to zero and disappears from the result.
The calculator also handles fractional and negative coefficients. For a term like 6x⁴, the derivative is 24x³ (multiply 6 by 4, reduce the exponent by 1). For 0.5x², the derivative is x (multiply 0.5 by 2, reduce the exponent by 1). The result is always a polynomial of one degree lower than the input, because each term’s exponent decreases by one.How to use
- Enter the coefficients from highest degree to constant, separated by commas.
- For example, enter 3,2,5,7 for 3x³ + 2x² + 5x + 7.
- Click Calculate to get the derivative.
- Review the step-by-step differentiation of each term.
- Notice that the constant term drops out of the result.
Frequently Asked Questions
What happens to the constant term?
The derivative of any constant is zero. This is because a constant does not change, so its rate of change is zero. When you differentiate 3x² + 5x + 7, the constant 7 produces 0 and simply disappears from the result. This is why you lose information when differentiating: you cannot recover the original constant from the derivative alone.
Can this calculator handle trigonometric or exponential functions?
No. This calculator uses the polynomial power rule, which applies only to terms of the form c·xⁿ. Trigonometric functions (d/dx sin x = cos x), exponentials (d/dx e^x = e^x) and logarithms (d/dx ln x = 1/x) require different rules that this tool does not cover.
What is the difference between derivative and integral?
Differentiation and integration are inverse operations. Differentiation breaks a function down into its rate of change, while integration builds up a function from its rate of change. If you differentiate a function and then integrate the result, you get back the original function plus a constant C. Together they form the Fundamental Theorem of Calculus.
What does the derivative tell you geometrically?
The derivative at a point gives the slope of the tangent line to the function at that point. Where the derivative is positive, the function is increasing; where it is negative, the function is decreasing; where it is zero, the function has a horizontal tangent (a local maximum, minimum or inflection point).
Tips & Advice
When differentiating polynomials, apply the power rule to each term: multiply the coefficient by the exponent, then reduce the exponent by 1. A common mistake is reducing the exponent without multiplying: d/dx [x³] = 3x², not x². Another common error is forgetting that constants vanish: many students leave the constant term in the derivative. To check your work, integrate the result: you should get back the original polynomial plus an arbitrary constant C. In optimization problems, set the derivative equal to zero to find critical points (where the function may have a maximum or minimum). The second derivative tells you whether a critical point is a maximum (second derivative negative) or a minimum (second derivative positive). In machine learning, the derivative of the loss function with respect to each parameter tells you how to adjust that parameter to reduce the loss, which is the core of gradient descent.
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