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a) Ta có:
\(7^{2006}-7^{2005}+7^{2004}\)
\(=7^{2004}\left(7^2-7+1\right)\)
\(=7^{2004}\times43\)
\(\Rightarrow7^{2006}-7^{2005}+7^{2004}\)chia hết cho 43 (vì có chứa thừa số 43)
b) Ta có:
\(32^{17}+16^{21}-2^{82}\)
\(=\left(2^5\right)^{17}+\left(2^4\right)^{21}-2^{82}\)
\(=2^{85}+2^{84}-2^{82}\)
\(=2^{82}\left(2^3+2^2-1\right)=2^{82}\times11=2^{80}\times2^2\times11\)
\(=2^{80}\times44\)
\(\Rightarrow32^{17}+16^{21}-2^{82}\)chia hết cho 44 (vì có chứa thừa số 44)
a) \(\dfrac{-12}{17}< \dfrac{x}{17}< \dfrac{-8}{17}\)
\(\Rightarrow-12< x< -8\)
\(\Rightarrow x\in\left\{-11;-10;-9\right\}\)
b) \(\dfrac{-1}{2}< x< \dfrac{5}{3}\)
\(\Rightarrow\dfrac{-3}{6}< x< \dfrac{10}{6}\)
\(\Rightarrow x\in\left\{\dfrac{-2}{6};\dfrac{-1}{6};0;\dfrac{1}{6};...;\dfrac{7}{6};\dfrac{8}{6};\dfrac{9}{6}\right\}\)
c) \(3,456< x\le7,89\)
\(\Rightarrow x\in\left\{3,456;3,457,3,458;...;7,89\right\}\)
d) \(5,82< \overline{5,8x0}< 8,845\)
\(\Rightarrow x\in\left\{3;4\right\}\)
e) \(32,82< \overline{3x,850}< 35,845\)
\(\Rightarrow x\in\left\{3;4\right\}\)
\(\dfrac{15}{34}+\dfrac{7}{21}+\dfrac{19}{34}-\dfrac{32}{17}+\dfrac{2}{3}\)
\(=\left(\dfrac{15}{34}+\dfrac{19}{34}\right)+\dfrac{7}{21}+\dfrac{-32}{17}+\dfrac{2}{3}\)
\(=1+\dfrac{1}{3}+\dfrac{-32}{17}+\dfrac{2}{3}\)
\(=1+\left(\dfrac{1}{3}+\dfrac{2}{3}\right)+\dfrac{-32}{17}\)
\(=1+1+\dfrac{-32}{17}\)
\(2+\dfrac{-32}{17}=\dfrac{2}{17}\)
c: \(=\dfrac{3}{2}\cdot1-1-20=\dfrac{3}{2}-21=\dfrac{-39}{2}\)
Ta có : \(32^{17}+16^{21}-2^{82}=\left(2^5\right)^{17}+\left(2^4\right)^{21}-2^{82}=2^{85}+2^{84}-2^{82}\)
\(=2^{80}.2^5+2^{80}.2^4-2^{80}.2^2=2^{80}.\left(2^5+2^4-2^2\right)=2^{80}.44⋮44\)
Vậy \(32^{17}+16^{21}-2^{82}⋮44\left(đpcm\right)\)