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Question-74840




Question Number 74840 by aliesam last updated on 01/Dec/19
Commented by kaivan.ahmadi last updated on 01/Dec/19
a^4 =1⇒  b^4 =a^4 =1⇒o(b)=4  (a^2 )^2 =1⇒o(a^2 )=2  o(a^3 )=o(a.a^2 )=((o(a)o(a^2 ))/((o(a),o(a^2 ))))=((2×4)/2)=4  o(ab)=((o(a)o(b))/((o(a),o(b))))=((4×4)/4)=4  o(a^2 b)=((2×4)/2)=4  o(a^3 b)=((4×4)/4)=4
$${a}^{\mathrm{4}} =\mathrm{1}\Rightarrow \\ $$$${b}^{\mathrm{4}} ={a}^{\mathrm{4}} =\mathrm{1}\Rightarrow{o}\left({b}\right)=\mathrm{4} \\ $$$$\left({a}^{\mathrm{2}} \right)^{\mathrm{2}} =\mathrm{1}\Rightarrow{o}\left({a}^{\mathrm{2}} \right)=\mathrm{2} \\ $$$${o}\left({a}^{\mathrm{3}} \right)={o}\left({a}.{a}^{\mathrm{2}} \right)=\frac{{o}\left({a}\right){o}\left({a}^{\mathrm{2}} \right)}{\left({o}\left({a}\right),{o}\left({a}^{\mathrm{2}} \right)\right)}=\frac{\mathrm{2}×\mathrm{4}}{\mathrm{2}}=\mathrm{4} \\ $$$${o}\left({ab}\right)=\frac{{o}\left({a}\right){o}\left({b}\right)}{\left({o}\left({a}\right),{o}\left({b}\right)\right)}=\frac{\mathrm{4}×\mathrm{4}}{\mathrm{4}}=\mathrm{4} \\ $$$${o}\left({a}^{\mathrm{2}} {b}\right)=\frac{\mathrm{2}×\mathrm{4}}{\mathrm{2}}=\mathrm{4} \\ $$$${o}\left({a}^{\mathrm{3}} {b}\right)=\frac{\mathrm{4}×\mathrm{4}}{\mathrm{4}}=\mathrm{4} \\ $$
Commented by kaivan.ahmadi last updated on 01/Dec/19
a.a^3 =1⇒a^(−1) =a^3  ,(a^3 )^(−1) =a  (a^2 )^2 =1⇒(a^2 )^(−1) =a^2   (a^2 b)b=a^2 b^2 =b^2 b^2 =b^4 =1⇒(a^2 b)^(−1) =b,b^(−1) =a^2 b
$${a}.{a}^{\mathrm{3}} =\mathrm{1}\Rightarrow{a}^{−\mathrm{1}} ={a}^{\mathrm{3}} \:,\left({a}^{\mathrm{3}} \right)^{−\mathrm{1}} ={a} \\ $$$$\left({a}^{\mathrm{2}} \right)^{\mathrm{2}} =\mathrm{1}\Rightarrow\left({a}^{\mathrm{2}} \right)^{−\mathrm{1}} ={a}^{\mathrm{2}} \\ $$$$\left({a}^{\mathrm{2}} {b}\right){b}={a}^{\mathrm{2}} {b}^{\mathrm{2}} ={b}^{\mathrm{2}} {b}^{\mathrm{2}} ={b}^{\mathrm{4}} =\mathrm{1}\Rightarrow\left({a}^{\mathrm{2}} {b}\right)^{−\mathrm{1}} ={b},{b}^{−\mathrm{1}} ={a}^{\mathrm{2}} {b} \\ $$$$ \\ $$
Commented by kaivan.ahmadi last updated on 02/Dec/19

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