Question

Tính tổng:

A=3^1+3^2+3^3+...+3^100

Answer 1

Giải:

A=3+3^2+3^3+...+3^100

3A=3^2+3^3+3^4+...+3^101

3A-A=(3^2+3^3+3^4+...+3^101)-(3+3^2+3^3+...+3^100)

2A=3^101-3

A=(3^101-3):2

Answer 2

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Answer 3

Tính tổng:

A=3^1+3^2+3^3+...+3^100

A=3^{(1+2+3+4+...+99+100)}

A=3^{(100+1)x100:2}

A=3^101x100:2

A=3^10100:2

A=3⁵⁰⁵⁰