Quick reference table
Memorise these basic derivatives. Every other derivative is built from them using the combination rules below.
| f(x) | f′(x) |
|---|---|
The power rule
Bring the exponent down as a coefficient, then subtract one from the exponent. The rule holds for every real n, not just positive integers. That makes it the fastest way to handle roots and reciprocals once you rewrite them as powers.
- √x = x^(1/2), so its derivative is (1/2)x^(−1/2) = 1/(2√x).
- 1/x³ = x^(−3), so its derivative is −3x^(−4) = −3/x⁴.
- Constants differentiate to 0, and a constant factor stays put: (5x²)′ = 10x.
Product and quotient rules
Use the product rule whenever two non-constant factors are multiplied. The quotient rule is the product rule applied to f·g⁻¹, and is worth memorising for speed. The numerator starts with the derivative of the top: “low d-high minus high d-low, over low squared.”
Before reaching for the quotient rule, check whether simplifying first is easier. (x³ + x)/x is just x² + 1 for x ≠ 0.
The chain rule
The chain rule handles compositions, meaning a function inside another function. Identify the outer function, differentiate it while leaving the inside untouched, then multiply by the derivative of the inside. For nested compositions, repeat from the outside in.
- (3x + 1)⁵ → 5(3x + 1)⁴ · 3
- e^(x²) → e^(x²) · 2x
- ln(cos x) → (1/cos x) · (−sin x) = −tan x
Logarithmic differentiation
When both the base and the exponent contain x, as in xˣ, none of the basic rules apply directly. Take logarithms first: if y = xˣ then ln y = x ln x. Differentiate both sides (y′/y = ln x + 1) and multiply by y.
A strategy that works every time
- Simplify first: expand small products, cancel common factors, rewrite roots and reciprocals as powers.
- Look at the outermost operation. A sum calls for the sum rule, a product for the product rule, a quotient for the quotient rule, and a function of something other than x for the chain rule.
- Apply that one rule, then repeat on each smaller piece.
- Simplify the result and sanity-check it, for example by plugging in a value or comparing with a graph.
The derivative calculator follows exactly this outside-in process and labels each step with the rule it used, so you can compare your own work line by line.
