`3+1/9+3/9+2+5/9+3+2`

`= ( 3 +2+3+2) +(1/9+ 3/9 + 5/9)`

`= 10 + 9/9`

`=10 + 1`

`=11`

\(3+\dfrac{1}{9}+\dfrac{3}{9}+2+\dfrac{5}{9}+3+2\)

\(=3+\left(\dfrac{1}{9}+\dfrac{3}{9}+\dfrac{5}{9}\right)+2+3+2\)

\(=\left(3+2+3+2\right)+\dfrac{9}{9}\)

\(=10+1=11\)

18 phần11 nhân4 phần5 trừ7 phần11 nhân4 phần5 cộng9 phần3 nhân2 phần5

\(\dfrac{2}{3}+\dfrac{7}{13}-\dfrac{17}{9}+\dfrac{19}{13}-\dfrac{1}{9}+\dfrac{7}{3}\)

\(=\left(\dfrac{2}{3}+\dfrac{7}{3}\right)+\left(\dfrac{7}{13}+\dfrac{19}{13}\right)-\left(\dfrac{17}{9}+\dfrac{1}{9}\right)\)

\(=\dfrac{9}{3}+\dfrac{26}{13}-\dfrac{18}{9}\)

\(=3+2-2\)

\(=3\)

\((\frac{1}{2}+\frac{1}{4}+\frac{1}{6}) \)x \((\frac{36}{9}-\frac{12}{9}:\frac{1}{3}) \)

\(= (\frac{1}{2}+\frac{1}{4}+\frac{1}{6}) \) x \((\frac{36}{9}-\frac{36}{9})\)

\( = (\frac{1}{2}+\frac{1}{4}+\frac{1}{6}) \) x \(0\)

\(= 0\)

\(\left(\dfrac{2}{7}+\dfrac{5}{7}\right)+\left(\dfrac{3}{5}+\dfrac{2}{5}\right)+\left(\dfrac{3}{8}+\dfrac{4}{8}+\dfrac{1}{8}\right)+\left(\dfrac{1}{9}+\dfrac{8}{9}\right)=1+1+1+1=4\)

(2/7 + 5/7) + (3/5 + 2/5) + (3/8 + 4/8 + 1/8) + (1/9 + 8/9 )

= 1  +       1                   +         1             +        1         =  4

7/19x(1/3+2/3)

=7/19x1

=7/19

NHỚ K CHO MÌNH NẾU ĐÚNG NHÉ

= 7/19x(1/3+2/3)

= 7/19x1

= 7/19

:)))))))

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

( 1×2×3×......×9×10 ) × ( 218 × 37 - 109×74)

= ( 1×2×3×......×9×10 ) × ( 8066 - 8066)

= ( 1×2×3×......×9×10 ) × 0

= 0

\(\left(1\times2\times3\times...\times9\times10\right)\times\left(218\times37-109\times74\right)=\) 

\(=\left(1\times2\times3\times...\times9\times10\right)\times\left(8066-8066\right)\) 

\(=\left(1\times2\times3\times...\times9\times10\right)\times0\) 

\(=0\)

\(=\left(1\cdot2\cdot3\cdot...\cdot10\right)\cdot\left[37\cdot109\left(2-2\right)\right]=0\)

\(=\dfrac{3}{7}\left(\dfrac{5}{4}-\dfrac{2}{9}\right)=\dfrac{3}{7}\cdot\dfrac{45-8}{36}=\dfrac{3}{36}\cdot\dfrac{37}{7}=\dfrac{37}{84}\)

\(\dfrac{3}{7}:\dfrac{4}{5}-\dfrac{3}{7}:\dfrac{9}{2}\)
\(=\dfrac{3}{7}\times\dfrac{5}{4}-\dfrac{3}{7}\times\dfrac{2}{9}\)
\(=\dfrac{3}{7}\times\left(\dfrac{5}{4}-\dfrac{2}{9}\right)\)
\(=\dfrac{3}{7}\times\left(\dfrac{45}{36}-\dfrac{8}{36}\right)\)
\(=\dfrac{3}{7}\times\dfrac{37}{36}\)
\(=\dfrac{37}{84}\)
#DatNe

a: =20/90+15/90+54/90=89/90

b: =(9/13+4/13)+2/3=1+2/3=5/3