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Differentiate exponential functions

Differentiation of exponential functions establishes that ddxex=ex\frac{d}{dx}e^x=e^x and, for a positive constant base a1a\ne1, ddxax=axlna\frac{d}{dx}a^x=a^x\ln a, interpreting the derivative as an instantaneous rate proportional to the function’s current value. The chain rule extends these relationships to expressions such as eu(x)e^{u(x)} and au(x)a^{u(x)}, while distinguishing the special role of base ee from other bases; variable-base exponentials and more advanced generalizations are not included.

Detailed Explanation: Differentiate exponential functions

For exponential functions, use these basic rules:

ddxex=ex\frac{d}{dx}e^x=e^x

For a positive constant base a1a\ne 1,

ddxax=axln(a).\frac{d}{dx}a^x=a^x\ln(a).

If the exponent is a function u(x)u(x), use the chain rule:

ddxeu(x)=eu(x)u(x)\frac{d}{dx}e^{u(x)}=e^{u(x)}u'(x)

and

ddxau(x)=au(x)ln(a)u(x).\frac{d}{dx}a^{u(x)}=a^{u(x)}\ln(a)\,u'(x).

The factor ln(a)\ln(a) is needed for bases other than ee. The derivative is proportional to the function’s current value.

Example

Differentiate

f(x)=e3x21+2x+4.f(x)=e^{3x^2-1}+2^{x+4}.

Step 1: Differentiate the first term.

The exponent is

u(x)=3x21,u(x)=3x^2-1,

so

u(x)=6x.u'(x)=6x.

Using the chain rule,

ddxe3x21=e3x21(6x).\frac{d}{dx}e^{3x^2-1} =e^{3x^2-1}(6x).

There is no ln(e)\ln(e) factor because ln(e)=1\ln(e)=1.

Step 2: Differentiate the second term.

The exponent is

v(x)=x+4,v(x)=x+4,

so

v(x)=1.v'(x)=1.

Since the base is 22, include the factor ln(2)\ln(2):

ddx2x+4=2x+4ln(2)(1)=2x+4ln(2).\frac{d}{dx}2^{x+4} =2^{x+4}\ln(2)(1) =2^{x+4}\ln(2).

Step 3: Combine the results.

Therefore,

f(x)=6xe3x21+2x+4ln(2).\boxed{f'(x)=6x e^{3x^2-1}+2^{x+4}\ln(2)}.

For each exponential term, keep the original exponential, multiply by ln(base)\ln(\text{base}) when the base is not ee, and then multiply by the derivative of the exponent.

Learn by doing: Differentiate exponential functions

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Derivative Rules - General Exponential Exponent with Power to Derivative


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