TL

1+2+3+4+5+6+7+8+9=45

nha bn

HT

1+2+3+...+9

=(1+9)+(2+8)+...+5

=10+10+...+5

=10.4+5

=45

HT

45

nha bn

HT

OK

  \(\dfrac{26}{7}\) x \(\dfrac{11}{3}-\dfrac{26}{7}\) x \(\dfrac{2}{3}-\dfrac{6}{3}\) x \(\dfrac{26}{7}\)

\(=\dfrac{26}{7}\) x \(\left(\dfrac{11}{3}-\dfrac{2}{3}-\dfrac{6}{3}\right)\)

\(=\dfrac{26}{7}\) x \(\dfrac{3}{3}\)

\(=\dfrac{26}{7}\) x \(1=\dfrac{26}{7}\)

26/7 x 11/3 - 26/7 x 2/3 - 6/3 x 26/7

=( 11/3 - 2/3 - 6/3 ) x26/7

=      1 x 26/7

=         26 /7

Tick cho mình nha

267267 x 113−267113−267 x 23−6323−63 x 267267

=267=267 x (113−23−63)(113−23−63)

=267=267 x 3333

=267=267 x 1=267

+1

(9+1) + ( 2 + 8 ) + ( 3 + 7) + ( 4 + 6 ) + 5
=10 + 10 + 10 + 10 + 5 
= 10 x 4 + 5
= 40 + 5
= 45

1+2+3+4+5+6+7+8+9

= ( 1 + 9 ) +  ( 2 + 8 ) + ( 3 + 7 ) + ( 4 + 6 ) + 5

= 10  x 4 + 5

= 45

~HT~

@Anh

1 + 2 + 3 + 4 + 5 + 6 + 7 +8 +9

=(1+9) + (2+8) + (3+7) + (4+6) + 5

=10 + 10 + 10 + 10 + 5

=45

Nhớ k đúng cho mk nha, thanks

--------_HT_---------

1,

a,=4/7:4/9.3

=9/7.3

=27/7

b,=(7/11+4/11).5/6

=1.5/6

=5/6

`(6/7-2/7):4/9xx3=4/7xx9/4xx3=[4xx9xx3]/[7xx4]=27/7`

`7/11xx5/6+4/11xx5/6=(7/11+4/11)xx5/6=11/11xx5/6=5/6`

(9+1)+(2+8)+(3+7)+(4+6)+10+5

(9+1) +(7+3)+(6+4) +(8+2)+(10+5)

=10+10+10+10+15

=55