Use ^ for powers and * for multiplication. Supports sin, cos, tan, exp, ln, log, sqrt, e, pi.
Step-by-step solution
Worked example: f(x) = x³ + 2x² − 5x + 1
Step 1 — Sum rule: differentiate term by term.
Step 2 — Power rule on x³ → 3x². Constant multiple + power rule on 2x² → 4x. Power rule on −5x → −5. Constant rule on 1 → 0.
Answer: f′(x) = 3x² + 4x − 5.
Evaluate at x = 2: f′(2) = 3(4) + 4(2) − 5 = 12 + 8 − 5 = 15. And f(2) = 8 + 8 − 10 + 1 = 7, so the tangent line at x = 2 is y = 15(x − 2) + 7, i.e. y = 15x − 23.
Type this exact function into the calculator above with x = 2 in the evaluate box — you'll get the same steps, the same 15, and the same tangent line.
The 5 differentiation rules (with one-line examples)
| Rule | When to use it | Example |
|---|---|---|
| Power rule | x raised to a number | d/dx[x⁵] = 5x⁴ |
| Constant multiple | a number times a function | d/dx[3x²] = 6x |
| Sum / difference | terms added or subtracted | d/dx[x² + x] = 2x + 1 |
| Product rule | two functions multiplied | d/dx[x²·sin(x)] = 2x·sin(x) + x²·cos(x) |
| Quotient rule | one function divided by another | d/dx[(x²+1)/(x−3)] — see steps above |
| Chain rule | a function inside a function | d/dx[sin(x²)] = 2x·cos(x²) |
The chain rule, properly explained
The chain rule is where most marks are lost, so it deserves its own section. Think outside-in:
- Differentiate the outer function, leaving the inner part untouched.
- Multiply by the derivative of the inner function.
For sin(x²): the outer derivative is cos(x²); the inner derivative of x² is 2x. Multiply: 2x·cos(x²). The classic mistake is stopping at cos(x²) and forgetting the × 2x. The calculator's steps call this out explicitly every time it applies the chain rule.
Second derivatives
The first derivative f′(x) measures the rate of change; the second derivative f″(x) measures how that rate itself changes — the curvature of the graph. Select “2nd derivative” above and the calculator differentiates twice, showing both rounds of steps. For f(x) = x⁴: f′(x) = 4x³, then f″(x) = 12x².
Why the steps are shown, not hidden
Most online derivative tools either hide the working behind an “expand” button, require an account, or route your homework through an AI and make you wait. This calculator does the differentiation symbolically in your browser — no account, no waiting — and prints every rule it applies, in order, with the intermediate expression. If a function uses a form the step engine doesn't cover yet (like xˣ), it still gives you the exact symbolic answer and says so honestly instead of inventing steps.
Common mistakes to avoid
- Forgetting the chain rule's inner derivative — d/dx[sin(3x)] is 3cos(3x), not cos(3x).
- Sign errors on trig functions — d/dx[cos(x)] = −sin(x). The minus sign is the whole battle.
- Product rule ≠ multiply the derivatives — (uv)′ is u′v + uv′, not u′v′.
- Quotient rule order — it's (u′v − uv′)/v². Swap the subtraction and the sign flips.
- Constants vanish — the +1 in x³+2x²−5x+1 contributes nothing to the derivative.