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Romaniulian87
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HELP!
0,1(a) + 0,(a) +0,a(1) e N , a=? 21, 12 ,10,4,18?

Răspuns :

Renatemambouko
(10+a-1)/90+a/9+(10a+1-a)/90 ∈N
(10+a-1)/90+a/9+(10a+1-a)/90=
=(9+a)/90+a/9+(9a+1)/90=
=(10a+10)/90+a/9=
=(a+1)/9+a/9=
=(2a+1)/9
2a+1 = multiplu de 9
a=4


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