Răspuns :

[tex]\red{\large \boxed {\bf S = a_{1} + a_{2}+ n = 2023}}[/tex]

Explicație pas cu pas:

Bună

[tex] \large\bf {2}^{2021} \cdot {5}^{2020} = \overline{a_{1}a_{2}....a_{n}}[/tex]

[tex]\large \bf \overline{a_{1}a_{2}....a_{n}} = {2}^{2020} \cdot2\cdot {5}^{2020} [/tex]

[tex]\large\bf \overline{a_{1}a_{2}....a_{n}} = 2 \cdot(2\cdot 5)^{2020} [/tex]

[tex]\large\bf \overline{a_{1}a_{2}....a_{n}} = 2 \cdot10^{2020} [/tex]

[tex]\large\bf \overline{a_{1}a_{2}....a_{n}} = 2 \cdot 1 \underset{ 2020 \: zerouri}{\underbrace{000.......00 }}[/tex]  

[tex]\large\bf \overline{a_{1}a_{2}....a_{n}} = 2 \underset{ 2020 \: zerouri}{\underbrace{000......00 }}[/tex]

[tex]\large\bf \overline{a_{1}a_{2}....a_{n}} = 2 \underset{ 2020 \: zerouri}{\underbrace{000......00 }} \implies 2021~ cifre[/tex]

[tex]\bf \large S = a_{1} + a_{2}+ n \implies S = 2 + 0 + 2021 \implies[/tex]

[tex]\red{\large \boxed{ \bf \: S = 2023}}[/tex]

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