Question

so sanh 

7^98+7^99+7^100 va 7^101

Answer 1

7⁹⁸ + 7⁹⁹ + 7¹⁰⁰ và 7¹⁰¹

Bên 7⁹⁸ + 7⁹⁹ + 7¹⁰⁰ ta tính như sau:

7⁹⁸ + 7⁹⁹ + 7¹⁰⁰  = 7^{98 + 99 + 100} = 7²⁹⁷

Vì 7²⁹⁷ > 7¹⁰¹ nên 7⁹⁸ + 7⁹⁹ + 7¹⁰⁰ > 7¹⁰¹

Answer 2

A=7^98+7^99+7^100

7A=7.7^98+7.7^99+7.7^100

7A=7^99+7^100+7^101

7A-A=(7^99+7^100+7^101)-(7^98+7^99+7^100)

=> 6A=7^101-7^98

=> A=(7^101-7^98):6

Mà: B=7^101

=> A<B

=> 7^98+7^99+7^100<7^101.

K nhé, tui cảm ơn.

Answer 3

Ta có\(7^{98}+7^{99}+7^{100}=7^{98}.\left(1+7^1+7^2\right)=7^{98}.57\)

\(7^{101}=7^{98}.7^3=7^{98}.343\)

vì \(343>57\Rightarrow7^{98}.343>7^{98}.57\Rightarrow7^{101}>7^{98}+7^{99}+7^{100}\)

Answer 4

Ta có : \(7^{98}+7^{99}+7^{100}=7^{98}\left(1+7+7^2\right)=7^{98}\cdot57\)

          \(7^{101}=7^{98}.7^3=7^{98}\cdot343\)

           Vì \(7^{98}\cdot57< 7^{98}\cdot343\)

          Nên  \(7^{98}+7^{99}+7^{100}< 7^{101}\)

Phần này mk ko giỏi lắm ko chắc đâu nha