Calculus⏱ 5 min read

Power Rule (Derivatives)

d/dx[xⁿ] = nxⁿ⁻¹

📖 What is the Power Rule?

The power rule is the most fundamental rule in differential calculus. It allows you to differentiate any term with a variable raised to a power. To apply it: multiply by the exponent, then reduce the exponent by one.

d/dx[xⁿ] = n·xⁿ⁻¹

🔤 What Each Part Means

d/dx
Derivative with respect to xThe rate of change of the function as x changes
xⁿ
The functionx raised to the power n
n
The exponentCan be any real number: positive, negative, or fraction

📝 Step-by-Step Examples

1
d/dx[x³]

Multiply by exponent, reduce by 1

= 3x²
2
d/dx[5x⁴]

Constant multiplies through

= 5 × 4x³ = 20x³
3
d/dx[x⁻²]

Works with negative exponents too

= -2x⁻³ = -2/x³
4
d/dx[√x] = d/dx[x^(1/2)]

Works with fractional exponents

= (1/2)x^(-1/2) = 1/(2√x)

💡 Special Cases

Constant rule:
d/dx[c] = 0    (constants have zero rate of change)
Linear rule:
d/dx[x] = 1    (slope of y = x is always 1)
Integration (reverse):
∫xⁿ dx = xⁿ⁺¹/(n+1) + C
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🎯 Quick Fact

Newton and Leibniz independently invented calculus in the 1660s–1680s. They also both discovered the power rule.