A=3 mũ 2010-(3 mũ 2009+3 mũ 2008+3 mũ 2007+…..+3 mũ 2+3+1)

Đáp án :

`A=(3^(2010)+1)/2`

Giải thích các bước giải :

`A=3^(2010)-(3^(2009)+3^(2008)+3^(2007)+…+3^2+3+1)`

`+)Đặt  B=3^(2009)+3^(2008)+3^(2007)+…+3^2+3+1`

`<=>3B=3^(2010)+3^(2009)+3^(2008)+…+3^3+3^2+3`

`<=>3B-B=(3^(2010)+3^(2009)+…+3^2+3)-(3^(2009)+3^(2008)+…+3+1)`

`<=>2B=3^(2010)-1`

`<=>B=(3^(2010)-1)/2`

`<=>A=3^(2010)-(3^(2010)-1)/2`

`<=>A=[2.3^(2010)]/2-(3^(2010)-1)/2`

`<=>A=(2.3^(2010)-3^(2010)+1)/2`

`<=>A=(3^(2010)+1)/2`

Vậy `A=(3^(2010)+1)/2`

~Chúc bạn hoc tốt !!!~