Bài 7:

Số phần kẹo Hùng đã cho Hà và Hồng là:

\(\dfrac{2}{7}+\dfrac{1}{7}=\dfrac{3}{7}\left(phần\right)\)

Hùng còn lại số phần của gói kẹo là:

\(\dfrac{6}{7}-\dfrac{3}{7}=\dfrac{3}{7}\left(phần\right)\)

1:

 2 3/4

5 6/5

3 3/9

7 6/8

2:

1/3 + 2/3 + (3/4 + 1/4) = 2

=2

= 4 5/10

1:

\(2+\dfrac{3}{4}=\dfrac{8}{4}+\dfrac{3}{4}=\dfrac{11}{4};5+\dfrac{6}{5}=\dfrac{25}{5}+\dfrac{6}{5}=\dfrac{31}{5};\dfrac{3}{9}+3=\dfrac{1}{3}+\dfrac{9}{3}=\dfrac{10}{3}\)

2: 

a: \(=\left(\dfrac{1}{3}+\dfrac{2}{3}\right)+\left(\dfrac{3}{4}+\dfrac{1}{4}\right)\\ =1+1=2\)

b: \(=\left(\dfrac{3}{4}+\dfrac{2}{8}\right)+\left(\dfrac{3}{5}+\dfrac{4}{10}\right)\\ =\left(\dfrac{6}{8}+\dfrac{2}{8}\right)+\left(\dfrac{6}{10}+\dfrac{4}{10}\right)\\ =1+1=2\)

c:\(=\left(\dfrac{1}{10}+\dfrac{9}{10}\right)+\left(\dfrac{2}{10}+\dfrac{8}{10}\right)+\left(\dfrac{3}{10}+\dfrac{7}{10}\right)+\left(\dfrac{4}{10}+\dfrac{6}{10}\right)+\dfrac{5}{10}\\ =1+1+1+1+\dfrac{5}{10}=4\dfrac{5}{10}\)

Ta có

\(\frac{1}{10}+\frac{2}{10}+\frac{3}{10}+\frac{4}{10}+\frac{5}{10}+\frac{6}{10}+\frac{7}{10}+\frac{8}{10}+\frac{9}{10}\)

\(=\frac{1+2+3+4+5+6+7+8+9}{10}\)

\(=\frac{\left(1+9\right)+\left(2+8\right)+\left(3+7\right)+\left(4+6\right)+5}{10}=\frac{10.4+5}{10}=\frac{45}{10}=\frac{9}{2}\)

Mình cũng làm như Trần Thuỳ Dung và bằng 9/2

mk cũng làm giống Trần Thùy Dung

1/10 + 2/10 + 3/10 + 4/10 + 5/10 + 6/10 + 7/10 + 8/10 + 9/10 

= { 1 + 9 } + { 2 + 8 } + { 3 + 7 } + { 4 + 6 } + 5

= 10 + 10 + 10 + 10 + 5

= 45

1/10+2/10+3/10+...+9/10=(1+2+3+4+.....+9)/10=45/10=4,5

=(1+2+3+4+5+6+7+8+9+10)/10=55/10

\(=\dfrac{1+2+3+4+5+6+7+8+9}{10}\\ =\dfrac{\left(1+9\right)+\left(2+8\right)+\left(3+7\right)+\left(4+6\right)+5}{10}\\ =\dfrac{10+10+10+10+5}{10}=\dfrac{45}{10}=\dfrac{9}{2}\)

9/2

\(a,3456731-19994=3436737\)

\(b,3\times31\times16+2\times24\times42+4\times27\times12\)

\(=\left(3\times16\right)\times31+\left(2\times24\right)\times42+\left(4\times12\right)\times27\)

\(=48\times31+48\times42+48\times27\)

\(=48\times\left(31+42+27\right)\)

\(=48\times100\)

\(=4800\)

\(c,\left(3^{10}+3^{12}\right):3^{10}\)

\(=3^{10}:3^{10}+3^{12}:3^{10}\)

\(=1+3^2\)

\(=1+9\)

\(=10\)

\(d,\left(2^{13}-3.2^{10}\right):2^{10}+\left(5^{10}-5^9\right):5^9\)

\(=2^{13}:2^{10}-3.2^{10}:2^{10}+5^{10}:5^9-5^9:5^9\)

\(=2^3-3+5-1\)

\(=8-3+5-1\)

\(=9\)

Bài 1: 

b) Ta có: \(D=\dfrac{-5}{10}\cdot\dfrac{-4}{10}\cdot\dfrac{-3}{10}\cdot...\cdot\dfrac{3}{10}\cdot\dfrac{4}{10}\cdot\dfrac{5}{10}\)

\(=\dfrac{-5}{10}\cdot\dfrac{-4}{10}\cdot\dfrac{-3}{10}\cdot...\cdot0\cdot...\cdot\dfrac{3}{10}\cdot\dfrac{4}{10}\cdot\dfrac{5}{10}\)

=0

0,2-0,375+5/11/-0,3+9/16-15/22

Giúp mik với! mik cần gấp trong 5 phút.

75

k mk nha

mk k lại cho!

3 + 4 + 5 + 5 + 6 + 7 + 8 + 10 + 10 + 3 + 4 + 5 + 5 + 6 + 7

= (3 + 7) + (3 + 7) + (4 + 6) + (4 + 6) + (5 + 5) + (5 + 5) + 10 + 10

=     10   +    10    +    10    +     10   +     10   +    10    + 10 + 10

=     80

=(3+7)+(4+6)+(5+5)+(3+7)+(4+6)+(5+5)+10+10

=10+10+10+10+10+10+10+10

=80