14/15 + 2/11 + 1/15 + 4/11 + 10/20 

=(14/15+1/15)+(2/11+4/11)+10/20

=1+6/11+10/20

=17/11+10/20

=45/22

Cái 17/11 à

1+6/11=17/11

bn ko hiểu chỗ nào bảo mik

\(\frac{14}{15}+\frac{2}{11}+\frac{1}{15}+\frac{4}{11}+\frac{10}{20}\)

\(=\left(\frac{14}{15}+\frac{1}{15}\right)+\left(\frac{2}{11}+\frac{4}{11}\right)+\frac{10}{20}\)

\(=1+\frac{6}{11}+\frac{10}{20}\)

\(=\frac{17}{11}+\frac{10}{20}\)

\(=\frac{45}{22}\)

a. $\dfrac{14}{15}+\dfrac{2}{11}+\dfrac{1}{15}+\dfrac{4}{11}+\dfrac{10}{22}$

$=(\dfrac{14}{15}+dfrac{1}{15})+(\dfrac{2}{11}+\dfrac{4}{11}+\dfrac{10}{22})$

$=1+1=2$

b. $74\times43-43+27\times43$

$=(74-1+27)\times43$

$=100\times43=4300$

\(a)\dfrac{14}{15}+\dfrac{2}{11}+\dfrac{1}{15}+\dfrac{4}{11}+\dfrac{10}{22}\)

\(=\left(\dfrac{14}{15}+\dfrac{1}{15}\right)+\dfrac{2}{11}+\dfrac{4}{11}+\dfrac{5}{11}\)

\(=1+1=2\)

\(b)74\times43-43+27\times43\)

\(=43\times\left(74-1+27\right)\)

\(=43\times100=4300\)

a) \(\dfrac{14}{15}+\dfrac{2}{11}+\dfrac{1}{15}+\dfrac{4}{11}+\dfrac{10}{22}\)

= \(\left(\dfrac{14}{15}+\dfrac{1}{15}\right)+\left(\dfrac{2}{11}+\dfrac{4}{11}\right)+\dfrac{5}{11}\)

= \(1+\dfrac{6}{11}+\dfrac{5}{11}\)

= 2

b) 74 x 43 - 43 + 27 x 43

= 74 x 43 - 43 x 1 + 27 x 43

= 43 x ( 74 - 1 + 27 )

= 43 x 100

= 4300

14/15 + 6/11 + 1/15 + 5/11 + 22/11

=(14/15 +1/15)+(6/11 + 5/11 + 22/11)

=1+3

=4

14/15+3/11+1/15+3/11=10/22

=[14/15+1/15]+[3/11+3/11]

=[14/15+1/15]+[3/11*2]

= 1+6/11

=17/11

sai bet!!

1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19

=(1+19)+(2+18)+(3+17)+(4+16)+(5+15)+(6+14)+(7+13)+(8+12)+(9+11)+10

=20+20+20+20+20+20+20+20+20+10

=20*9+10

=180+10=190

1+2+3+4+5+6+7+8+9+10+11+12+13 +14 +15+16+17+18+19

= 19 - 1( tức là trừ đi số 10 vì nó tròn chục )

=  18 : 2

=  9 x ( 19 + 1 ) + 10

=  9 x 20 + 10

=   180 + 10

=    190

tick cho bạn bách trả lời là 190 đi ai tick cho cậu ấy mình sẽ đội ơn người đấy

a) 14/15 + 3/11 + 1/15 + 3/11 + 10/22

= ( 14/15 + 1/15 ) + ( 3/11 + 3/11 + 10/22 )

= 1 + 1

= 2 

b) 9,25 + 9,25 x 8 + 9,25

= 9,25 x ( 1 + 8 + 1)

= 9,25 x 10

= 92,5

a/ \(\frac{14}{15}+\frac{3}{11}+\frac{1}{15}+\frac{3}{11}+\frac{10}{22}=\left(\frac{14}{15}+\frac{1}{15}\right)+\left(\frac{3}{11}+\frac{3}{11}+\frac{2x5}{2x11}\right)=\)

\(=\frac{15}{15}+\frac{11}{11}=1+1=2\)

b/ 9,25+9,25x8+9,25=9,25(1+8+1)=9,25x10=92,5

92,5 nh bn

14/15 + 3/11 + 1/15 + 3/11 + 10/12

= ( 3/11 +  3/11) + (14/15 + 1/15) + 5/6

=  6/11                  +         1            + 5/6

=   6/11              +      5/6                  +1

=          91/66                           +1

=

Đ/S:  

mình trình bày hơi xấu, xin lỗi nha

bạn tự tính 91/66 + 1 nha

1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20

=(1+19)+(2+18)+(3+17)+(4+16)+(5+15)+(6+14)+(7+13)+(8+12)+(9+11)+20+10

=20+20+20+20+20+20+20+20+20+20+10

=20×10+10

=200+10

=210

= ( 1 + 19 ) + ( 2 + 18 ) + ( 3 + 17 ) + (4 + 16 ) + ( 5 + 15 ) + ( 6 + 14 ) + ( 7 + 13 ) + ( 8 + 12) + ( 9+ 11 ) + 20

= 20 + 20 + 20 +20 +  20 +20 + 20 + 20 + 20 +20

= 20 x 10

= 200

tui đầu tiên đó 

Ta có : \(1+2+3+...+19+20\)

          \(=\frac{\left(20+1\right).20}{2}=\frac{21.20}{2}=210\)