Răspuns:
Explicație pas cu pas:
Salutare!
a)
[tex]\bf n = 10^{2018} +10^{2017} -1[/tex]
[tex]\bf n = 10^{2018} +10^{2017} -1[/tex]
[tex]\bf n=1\underset{\it 2018~de~zerouri}{\underbrace{000..........000}}+1\underset{\it 2017~de~zerouri}{\underbrace{000..........000}}-1[/tex]
[tex]\bf n=11\underset{\it 2017~de~zerouri}{\underbrace{000..........000}}-1[/tex]
[tex]\bf n=11\underset{\it 2017~de~9}{\underbrace{99.........99}}[/tex]
[tex]\bf Numarul_{~cifrelor~lui~ n} = 2+2017 = 2019[/tex]
[tex]\large\boxed{\boxed{\bf Numarul_{~cifrelor~lui~ n} = 2019~ cifre}}[/tex]
b)
[tex]\bf Suma_{~cifrelor~lui~n}=1+1+\underset{\it 2017~de~9}{\underbrace{9+9+......+9+9}}[/tex]
[tex]\bf Suma_{~cifrelor~lui~n}=2+2017 \cdot 9[/tex]
[tex]\bf Suma_{~cifrelor~lui~n}=2+18153[/tex]
[tex]\large\boxed{\boxed{\bf Suma_{~cifrelor~lui~n}=18155}}[/tex]
PS: Daca esti pe telefon, te rog sa glisezi spre dreapta pentru a vedea rezolvarea completa
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