Rules for Derivatives
Finding derivatives becomes much easier when you know the basic rules. Let's break them down:
Rule 1: Derivative of a constant is always zero. If f(x) = 3, then f'(x) = 0. Constants don't change as x changes, so their rate of change is zero!
Rule 2: Power Rule states that if f(x) = ax^n, then f'(x) = n·ax^n−1. This rule is super useful - you multiply by the power and then reduce the power by 1. For example, the derivative of x^4 is 4x^3.
Rule 3: Constant Multiple Rule lets you pull constants outside the derivative. For f(x) = 3x², f'(x) = 3(2x) = 6x.
Rule 4: Sum Rule means you can find derivatives term by term. For f(x) = x⁴ + 12x², f'(x) = 4x³ + 24x.
Rule 5: Product Rule helps when multiplying functions. If f(x) = u·v, then f'(x) = (u·dv) + (v·du). For example, with f(x) = 2x−53x+2, f'(x) = 2x−5(3) + 3x+2(2).
Remember This! The Product Rule follows the pattern "first times derivative of second, plus second times derivative of first."
Rule 6: Quotient Rule works for fractions. If f(x) = u/v, then f'(x) = v⋅du−u⋅dv/v². Think "low d-high minus high d-low, over low squared."
Rule 7: Power Rule for Negative Exponents works just like the regular power rule. For f(x) = 2x^(-3), f'(x) = -6x^(-4).
The exponential function has a special property: the derivative of e^x is e^x - it's its own derivative!
Second derivatives (f"(x)) are just the derivatives of the first derivatives. They measure how the rate of change is itself changing.