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Albertoalahmad
a fost răspuns

Aratati ca numarul:
a) N = [tex] \frac{3x+12}{7} [/tex] : [tex]\frac{x+4}{21} [/tex] este natural ,oricare ar fi x∈N;
b) N =[tex]\frac{30}{2x+7} [/tex] : [tex] \frac{5}{6x+21} [/tex] este natural ,oricare ar fi x∈N;

Răspuns :

a) [tex]\dfrac{3x+12}{7}: \dfrac{x+4}{21}=\dfrac{3x+12}{7} \cdot \dfrac{21}{x+4}=\dfrac{3(x+4)}{7}\cdot \dfrac{21}{x+4}= \dfrac{3(x+4)}{1} \cdot \dfrac{3}{x+4}=3 \cdot 3= 9[/tex]
9€ N

b) [tex]\dfrac{30}{2x+7} : \dfrac{5}{6x+21}=\dfrac{30}{2x+7} \cdot \dfrac{6x+21}{5}=\dfrac{1}{2x+7} \cdot \dfrac{3(2x+7)}{1}=3[/tex]
3€N

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