PowerExpand[expr]
expands all powers of products and powers.
PowerExpand[expr,{x1,x2,…}]
expands only with respect to the variables xi.
PowerExpand
PowerExpand[expr]
expands all powers of products and powers.
PowerExpand[expr,{x1,x2,…}]
expands only with respect to the variables xi.
Details and Options
- PowerExpand converts
to
, whatever the form of
is. - PowerExpand also converts
to
, whatever the form of
is. - The transformations made by PowerExpand are correct in general only if
is an integer or
and
are positive real numbers. - PowerExpand converts Log[a^b] to bLog[a].
- PowerExpand in general disregards all issues of branches of multivalued functions, so may not preserve the numerical values of expressions.
- PowerExpand automatically threads over lists, as well as equations, inequalities and logic functions.
- PowerExpand has the option Assumptions, specifying assumptions to use.
- The default setting for the Assumptions option is Automatic, corresponding to a maximal set of assumptions.
- With Assumptionsassum, the transformations made by PowerExpand are correct whenever the assumptions assum are satisfied.
- With Assumptions:>$Assumptions, you can specify default assumptions for PowerExpand using Assuming.
Examples
open all close allBasic Examples (2)
Expand a square root, implicitly assuming positive real values:
PowerExpand[Sqrt[x y]]Without PowerExpand, no expansion is done:
Sqrt[x y]The expansion is only correct for positive real variables:
{Sqrt[x y], Sqrt[x]Sqrt[y]} /. {x -> -2, y -> -3}This gives a completely correct result:
PowerExpand[Sqrt[x y], Assumptions -> True]This gives a result correct under the specified assumptions:
PowerExpand[Sqrt[x y], Assumptions -> Pi / 2 < Arg[x] < Pi && Pi / 2 < Arg[y] < Pi]Scope (11)
Expand a power of a product; the result may not be correct everywhere:
PowerExpand[(x y) ^ a]The general formula for expanding a power of a product:
PowerExpand[(x y) ^ a, Assumptions -> True]Expand nested powers; the results may not be correct everywhere:
PowerExpand[Sqrt[z ^ 2]]PowerExpand[(a ^ x) ^ y]General formulas for expanding a nested power:
PowerExpand[Sqrt[z ^ 2], Assumptions -> True]PowerExpand[(a ^ x) ^ y, Assumptions -> True]Expand the logarithm of a power; the result may not be correct everywhere:
PowerExpand[Log[1 / z]]PowerExpand[Log[z ^ a]]The general formulas for expanding logarithms of powers:
PowerExpand[Log[1 / z], Assumptions -> True]PowerExpand[Log[z ^ a], Assumptions -> True]Expand the logarithm of a product; the result may not be correct everywhere:
PowerExpand[Log[x y]]The general formula for expanding the logarithm of a product:
PowerExpand[Log[x y], Assumptions -> True]Expand compositions of inverse trigonometric and trigonometric functions:
PowerExpand[ArcTan[Tan[x]]]This gives the universally correct formula:
PowerExpand[ArcTan[Tan[x]], Assumptions -> True]Compute an expansion valid under the specified assumptions:
PowerExpand[ArcTan[Cot[x]], Assumptions -> 0 < x < Pi]Expand the argument of a product:
PowerExpand[Arg[x y], Assumptions -> True]Expand only with respect to a and b:
PowerExpand[Sqrt[a b] + Sqrt[c d], {a, b}]Options (3)
Assumptions (3)
With the default setting Assumptions -> Automatic, the expansions are not always correct:
PowerExpand[Sqrt[z ^ 2]]{Sqrt[z ^ 2], z} /. z -> -1When the assumptions are specified, the result is correct under the given assumptions:
PowerExpand[Sqrt[z ^ 2], Assumptions -> z < 0]With Assumptions->True, PowerExpand gives a universally correct expansion formula:
PowerExpand[Sqrt[z ^ 2], Assumptions -> True]Applications (2)
Find universally correct expansion rules:
PowerExpand[(E ^ x) ^ y, Assumptions -> True]PowerExpand[(a b c) ^ (1 / 3), Assumptions -> True]Expand under specified assumptions:
PowerExpand[(E ^ x) ^ y, Assumptions -> 4 < Im[x] < 5]PowerExpand[Log[(a b) ^ c], Assumptions -> 3 < a < 5 && -2 < b < -1 && 7 < c < 9]Properties & Relations (5)
PowerExpand performs expansions valid under the given assumptions:
PowerExpand[(z ^ p) ^ (1 / p), Assumptions -> 0 < p < 1]With Assumptions->True, PowerExpand gives general expansion formulas:
PowerExpand[(z ^ p) ^ (1 / p), Assumptions -> True]Refine and Simplify perform expansions valid under the given assumptions:
Refine[(z ^ p) ^ (1 / p), Assumptions -> 0 < p < 1]Simplify[(z ^ p) ^ (1 / p), Element[1 / p, Integers]]Use FunctionExpand to get a different representation of
:
FunctionExpand[Sin[Sqrt[z ^ 2]]]Use PiecewiseExpand to represent the result as a piecewise function:
PiecewiseExpand[PowerExpand[Sqrt[z ^ 2], Assumptions -> True], Assumptions -> -Pi < Arg[z] ≤ Pi]PiecewiseExpand[PowerExpand[Sqrt[x y], Assumptions -> True], Assumptions -> -Pi < Arg[x] ≤ Pi && -Pi < Arg[y] ≤ Pi]Possible Issues (1)
The result given by PowerExpand with Assumptions->Automatic may be incorrect:
PowerExpand[Sqrt[(x - y) ^ 2] + Sqrt[(y - x) ^ 2]]Simplify[Sqrt[(x - y) ^ 2] + Sqrt[(y - x) ^ 2]]See Also
Expand Power Sqrt Distribute ComplexExpand Simplify FullSimplify FunctionExpand Refine
Function Repository: LogContract
Related Guides
History
Introduced in 1991 (2.0) | Updated in 1996 (3.0) ▪ 2007 (6.0)
Text
Wolfram Research (1991), PowerExpand, Wolfram Language function, https://reference.wolfram.com/language/ref/PowerExpand.html (updated 2007).
CMS
Wolfram Language. 1991. "PowerExpand." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2007. https://reference.wolfram.com/language/ref/PowerExpand.html.
APA
Wolfram Language. (1991). PowerExpand. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/PowerExpand.html
BibTeX
@misc{reference.wolfram_2026_powerexpand, author="Wolfram Research", title="{PowerExpand}", year="2007", howpublished="\url{https://reference.wolfram.com/language/ref/PowerExpand.html}", note=[Accessed: 12-June-2026]}
BibLaTeX
@online{reference.wolfram_2026_powerexpand, organization={Wolfram Research}, title={PowerExpand}, year={2007}, url={https://reference.wolfram.com/language/ref/PowerExpand.html}, note=[Accessed: 12-June-2026]}