Skip to main content
Global

5.4: Regra do expoente zero

  1. Last updated
  2. Save as PDF
  • Page ID
    169990

    • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)

    \( \newcommand{\dsum}{\displaystyle\sum\limits} \)

    \( \newcommand{\dint}{\displaystyle\int\limits} \)

    \( \newcommand{\dlim}{\displaystyle\lim\limits} \)

    \( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)

    ( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)

    \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

    \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)

    \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)

    \( \newcommand{\Span}{\mathrm{span}}\)

    \( \newcommand{\id}{\mathrm{id}}\)

    \( \newcommand{\Span}{\mathrm{span}}\)

    \( \newcommand{\kernel}{\mathrm{null}\,}\)

    \( \newcommand{\range}{\mathrm{range}\,}\)

    \( \newcommand{\RealPart}{\mathrm{Re}}\)

    \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

    \( \newcommand{\Argument}{\mathrm{Arg}}\)

    \( \newcommand{\norm}[1]{\| #1 \|}\)

    \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)

    \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    \( \newcommand{\vectorA}[1]{\vec{#1}}      % arrow\)

    \( \newcommand{\vectorAt}[1]{\vec{\text{#1}}}      % arrow\)

    \( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \( \newcommand{\vectorC}[1]{\textbf{#1}} \)

    \( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)

    \( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)

    \( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)

    \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \(\newcommand{\longvect}{\overrightarrow}\)

    \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)

    \(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)

    Na seção 5.3, o expoente do número no numerador sempre foi maior do que o expoente do número no denominador.

    Na seção 5.4, o expoente do número no numerador será igual ao expoente do número no denominador.

    Definição: A regra do expoente zero

    Para qualquer número real\(a\), a Regra do Expoente Zero é a seguinte

    \(a^0= 1\)

    Ideia:

    Das seções anteriores:

    \[x^5 = x \cdot x \cdot x \cdot x \cdot x \nonumber \]

    e

    \[\dfrac{x^5 }{x^5} =\dfrac{ x \cdot x \cdot x \cdot x \cdot x }{x \cdot x \cdot x \cdot x \cdot x }= \dfrac{\cancel{x \cdot x \cdot x \cdot x \cdot x }}{\cancel{x \cdot x \cdot x \cdot x \cdot x }}= 1 \nonumber \]

    Conseqüentemente,

    \[\dfrac{x ^5 }{x^5} = x^{5−5 }= x^0=1 \nonumber \]

    Exemplo Template:index

    Use a regra do expoente zero para simplificar as expressões.

    1. \(\dfrac{x^9 }{x^9}\)
    2. \(\dfrac{d^5 }{d^2 \cdot d^3}\)
    3. \(\dfrac{5(xy)^3 }{(xy)^3}\)
    4. \(-\dfrac{y^3 }{\sqrt{5}y^3}\)
    5. \(\dfrac{(ab^2 )^7 }{(ab^2)^2 \cdot (ab^2)^4 ˙(ab^2)}\)
    Solução
    Expressão Regra do expoente zero
    \(\dfrac{x^9 }{x^9}\) \(x^{9−9} = x^0 = 1\)
    \(\dfrac{d^5 }{d^2 \cdot d^3}\) \(\dfrac{d^5 }{d^{2+3 }}= \dfrac{d^5 }{d^5} = d^{5−5 }= d^{0} = 1\)
    \(\dfrac{5(xy)^3 }{(xy)^3}\)

    \(5 \cdot \dfrac{(xy)^3 }{(xy)^3 }= 5 \cdot (xy)^{3−3 }= 5 \cdot (xy)^0 = 5 \cdot 1 = 5 \)

    A constante 5, pode ser considerada para ver claramente as bases comuns.
    \(-\dfrac{y^3 }{\sqrt{5}y^3}\)

    \(− \dfrac{1}{ \sqrt{5}} \cdot \dfrac{y^3 }{y^3 }= − \dfrac{1}{ \sqrt{5}} \cdot y ^{3−3 }= − \dfrac{1}{ \sqrt{5}} \cdot y^0 = − \dfrac{1}{ \sqrt{5}} \cdot 1 = − \dfrac{1}{ \sqrt{5}}\)

    A constante\(−\left( \dfrac{1 }{\sqrt{5}}\right )\) pode ser considerada para ver claramente as bases comuns.
    \(\dfrac{(ab^2 )^7 }{(ab^2)^2 \cdot (ab^2)^4 ˙(ab^2)}\)

    \(\dfrac{(ab^2 )^7 }{(ab^2)^{2+4+1}}= \dfrac{(ab^2 )^7}{ (ab^2)^7} = (ab^2 )^{7−7 }= (ab^2 )^0 = 1\)

    Primeiro, simplifique o denominador usando a regra do produto dos expoentes. Em seguida, use a regra do quociente dos expoentes para simplificar a expressão restante.

    Nota:\(0^0\) não é igual a 1. Este é um caso especial que é abordado em cursos avançados. Por enquanto, considere\(0^0\) como indefinido.

    Etapas úteis para simplificar expressões com expoentes

    1. Identifique bases comuns.
    2. Se necessário, combine bases comuns usando a regra do produto dos expoentes.
    3. Se a expressão contiver bases comuns no numerador e no denominador, use a regra do quociente dos expoentes conforme necessário.
    Exercício Template:index

    Use todas as regras de expoentes abordadas até agora neste capítulo para simplificar o seguinte.

    1. \(\dfrac{z ^4 }{z^ 4}\)
    2. \(\dfrac{d^2 \cdot d^8}{ d^7 \cdot d^3}\)
    3. \(\dfrac{5(x + y)^3 }{2(x + y)^3}\)
    4. \(−\dfrac{\sqrt{9}{y^3 }}{y^3}\)
    5. \(\dfrac{(a^3b^2 )^9}{ (a^3b^2)^3 \cdot (a^3b^2)^4 ˙(a^3b^2)^2}\)
    6. \(\dfrac{(xyz)^{19} }{(xyz)^{19}}\)
    Template:AutoNumHeadings

    This page titled 5.4: Regra do expoente zero is shared under a CC BY-SA 4.0 license and was authored, remixed, and/or curated by Victoria Dominguez, Cristian Martinez, and Sanaa Saykali (ASCCC Open Educational Resources Initiative) .