`6/11+2/5+16/11+19/13+3/5+7/13`

`=(6/11+16/11)+(2/5+3/5)+(19/13+7/13)`

`=22/11+5/5+26/13`

`=2+1+2=5`

\(=\left(\dfrac{6}{11}+\dfrac{16}{11}\right)+\left(\dfrac{2}{5}+\dfrac{3}{5}\right)+\left(\dfrac{19}{13}+\dfrac{7}{13}\right)\)

\(=2+1+2\)

\(=5\)

\(\frac{3}{5}+\frac{6}{11}+\frac{7}{13}+\frac{2}{5}+\frac{16}{11}+\frac{19}{13}=\left(\frac{3}{5}+\frac{2}{5}\right)\left(\frac{6}{11}+\frac{16}{11}\right)\left(\frac{7}{13}+\frac{19}{13}\right)=1+2+2=5\)

Ta có:3/5+2/5=5/5=1; 6/11+16/11=22/11=2; 7/13+19/13=26/13=2

kết quả là 1+2+2=5

\(\frac{3}{5}+\frac{6}{11}+\frac{7}{13}+\frac{2}{5}+\frac{16}{11}+\frac{19}{13}\)

\(=\left(\frac{3}{5}+\frac{2}{5}\right)+\left(\frac{6}{11}+\frac{16}{11}\right)+\left(\frac{7}{13}+\frac{19}{13}\right)\)

\(=\frac{5}{5}+\frac{22}{11}+\frac{26}{13}\)

\(=1+2+2=5\)

\(\left(\frac{3}{5}+\frac{2}{5}\right)+\left(\frac{6}{11}+\frac{16}{11}\right)+\left(\frac{7}{13}+\frac{19}{13}\right)\)

=         1             +                  2                +               2

= 5

\(=\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+\frac{1}{5\cdot6}+\frac{1}{6\cdot7}\)

=     \(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}\)

=\(1-\frac{1}{7}\)

=\(\frac{6}{7}\)

-4/11+5/6+7/11-5/6

=(-4/11+7/11)+(5/6-5/6)

=3/11+0

=3/11

Làm là giúp đủ 3 câu hộ mình. 1 câu k k đâu !

3/7*(0,5+11/2)-2/7:25%

=3/7*(0,5+11/2)-2/7:1/4

=3/7*(0,5+11/2)-2/7*4

=3/7*(1/2+11/2)-2/7*4

=3/7*6-2/7*4

=18/7-8/7

=10/7

a ] bằng1

bằng 5 cơ

mấy phần này nhìn thôi đã ko muốn làm rồi, lại còn giải chi tiết, đầy đủ nữa chứ!!!!!!!!!!!!!!

Bó tay!!!!!!!!!!!!!!!!!!

ác rứa

Giúp với tui cg bó bài này

Trả lời:

\(10+11+12+13+14+15+16+17+18+19+20\)

\(=\left(10+20\right)+\left(11+19\right)+\left(12+18\right)+\left(13+17\right)+\left(14+16\right)+15\)

\(=30+30+30+30+30+15\)

\(=165\)

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

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

\(=10+10+10+10+5\)

\(=45\)

10+11+12+13+14+15+16+17+18+19+20

(10+20)+(11+19)+(12+18)+(13+17)+(14+16)+15

30+30+30+30+30+15

165

\(a,\text{10 + 11 + 12 + 13 + 14 + 16 + 17 + 18 + 19 + 20}\)

\(=\left(10+20\right)+\left(11+19\right)+\left(12+18\right)+\left(13+17\right)+\left(14+16\right)\)

\(=30+30+30+30+30\)

\(=30\times5\)

\(=150.\)

\(b,\text{1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9}\)

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

\(=10+10+10+10+5\)

\(=45.\)