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Ta có A = 2¹ + 2² + 2³ + ... + 2²⁰¹¹⁰

= ( 2¹ + 2² ) + ( 2³ + 2⁴ ) + ... + ( 2²⁰⁰⁹ + 2²⁰¹⁰ )

= 2¹( 1 + 2 ) + 2³( 1 + 2 ) + ... + 2²⁰⁰⁹( 1 + 2 )

= 2¹ . 3 + 2³ . 3 + ... + 2²⁰⁰⁹ . 3

= 3( 2¹ + 2³ + ... + 2²⁰⁰⁹ ) ⋮ 3 vì 3 ⋮ 3

Vậy A ⋮ 3

3²-5x[3x(4-1)-8] 

= 9 - 5 x [ 3 x ( 4 - 1 ) - 8 ]
= 9 - 5 x [ 3 x 3 - 8 ]

= 9 - 5 x [ 9 - 8 ]

= 9 - 5 x 1

= 9 - 5

=4

`3^2 - 5xx[3xx(4-1)-8]`

`=9 - 5 xx [3 xx 3 - 8]`

`=9 - 5 xx ( 9-8)`

`=9 - 5 xx 1`

`=4`

Nếu bạn ko hiểu thì mik gửi ảnh cho:

       Chúc bạn học tốt!

Ta có: n3+n2+1⋮n+1" role="presentation" style="box-sizing: inherit; -webkit-tap-highlight-color: transparent; font-style: normal; font-weight: normal; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-size: 18.08px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;">n3+n2+1⋮n+1n3+n2+1⋮n+1 

⇔n2(n+1)+1⋮n+1" role="presentation" style="box-sizing: inherit; -webkit-tap-highlight-color: transparent; font-style: normal; font-weight: normal; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-size: 18.08px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;">⇔n2(n+1)+1⋮n+1⇔n2(n+1)+1⋮n+1

mà n2⋅(n+1)⋮n+1" role="presentation" style="box-sizing: inherit; -webkit-tap-highlight-color: transparent; font-style: normal; font-weight: normal; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-size: 18.08px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;">n2⋅(n+1)⋮n+1n2⋅(n+1)⋮n+1

nên 1⋮n+1" role="presentation" style="box-sizing: inherit; -webkit-tap-highlight-color: transparent; font-style: normal; font-weight: normal; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-size: 18.08px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;">1⋮n+11⋮n+1

⇔n+1∈Ư(1)" role="presentation" style="box-sizing: inherit; -webkit-tap-highlight-color: transparent; font-style: normal; font-weight: normal; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-size: 18.08px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;">⇔n+1∈Ư(1)⇔n+1∈Ư(1)

⇔n+1∈{1;−1}" role="presentation" style="box-sizing: inherit; -webkit-tap-highlight-color: transparent; font-style: normal; font-weight: normal; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-size: 18.08px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;">⇔n+1∈{1;−1}⇔n+1∈{1;−1}

hay n∈{0;−2}" role="presentation" style="box-sizing: inherit; -webkit-tap-highlight-color: transparent; font-style: normal; font-weight: normal; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-size: 18.08px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;">n∈{0;−2}n∈{0;−2}

Vậy: Để n3+n2+1⋮n+1" role="presentation" style="box-sizing: inherit; -webkit-tap-highlight-color: transparent; font-style: normal; font-weight: normal; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-size: 18.08px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;">n3+n2+1⋮n+1n3+n2+1⋮n+1 thì n∈{0;−2}" role="presentation" style="box-sizing: inherit; -webkit-tap-highlight-color: transparent; font-style: normal; font-weight: normal; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-size: 18.08px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;">n∈{0;−2}

     CHÚC BẠN HỌC TỐT!

`(5-x)(x+7)=0`

`@TH1:5-x=0=>x=5`

`@TH2:x+7=0=>x=-7`

Cho A=n.(n+3) + 2013 không chia hết cho 9

(2⁴³+2⁴):(2³⁹+1)

=2⁴⁷:2⁴⁰

=2⁴⁰

giúp mình với, mình đang cần gấp

Diện tích phần còn lại là:

`64-2=62(m^2)`

Số cây hoa trồng được là:

`62 xx 4 = 248(cây)`

Số tiền để mua hoa hồng là:

`248 xx 50.000 = 12400000(đồng)`

D/s....