a,(11/15+4/15)+(5/7+2/7)

=1+1

=2

b,5/9x(1/2+6/4)

=5/9x2

=10/9

c,1/2:(7/8+9/8)

=1/2:2

=1

d,(17/10-7/10)+1/2

=1+1/2

=3/2

a) \(\frac{11}{15}+\frac{5}{7}+\frac{2}{7}+\frac{4}{15}=\left(\frac{11}{15}+\frac{4}{15}\right)+\left(\frac{5}{7}+\frac{2}{7}\right)\)

\(=2\)

b) \(\frac{5}{9}\times\frac{1}{2}\times\frac{5}{9}\times\frac{6}{4}=\frac{25}{81}\times\frac{3}{4}=\frac{25}{108}\)

c) \(\frac{7}{8}\div\frac{1}{2}+\frac{9}{8}\div\frac{1}{2}=\left(\frac{7}{8}+\frac{9}{8}\right)\div\frac{1}{2}\)

\(=2\div\frac{1}{2}=4\)

d) \(\frac{17}{10}+\frac{1}{2}-\frac{7}{10}=\left(\frac{17}{10}-\frac{7}{10}\right)+\frac{1}{2}\)

\(=1+\frac{1}{2}=\frac{3}{2}\)

a) \(\frac{11}{15}+\frac{5}{7}+\frac{2}{7}+\frac{4}{15}\)

\(=\left(\frac{11}{15}+\frac{4}{15}\right)+\left(\frac{5}{7}+\frac{2}{7}\right)\)

\(=1+1\)

\(=2\)

b) \(\frac{5}{9}.\frac{1}{2}.\frac{5}{9}.\frac{6}{4}\)

\(=\left(\frac{5}{9}\right)^2\left(\frac{1}{2}.\frac{6}{4}\right)\)

\(=\frac{25}{81}.\frac{3}{4}\)

\(=\frac{25}{108}\)

c) \(\frac{7}{8}:\frac{1}{2}+\frac{9}{8}:\frac{1}{2}\)

\(=\frac{7}{8}.2+\frac{9}{8}.2\)

\(=2\left(\frac{7}{8}+\frac{9}{8}\right)\)

\(=2.\frac{16}{8}\)

\(=2.2\)

\(=4\)

d) \(\frac{17}{10}+\frac{1}{2}-\frac{7}{10}\)

\(=\left(\frac{17}{10}-\frac{7}{10}\right)+\frac{1}{2}\)

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

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

\(=\frac{3}{2}\)

a ) (11/15+4/15 ) + ( 5/7 +2 /7 )

=1+1

= 2

b)5/9 x ( 1/ 2 + 6/ 4 )

= 5/9 x 2

=10/9 

c) 17/10-5/10-7/10

=(17-5-7) / 10

= 5/10

\(2\frac{3}{5}=\frac{2x5+3}{5}=\frac{10+3}{5}=\frac{13}{5}\)

\(5\frac{4}{9}=\frac{5x9+4}{9}=\frac{45+4}{9}=\frac{49}{9}\)

\(9\frac{3}{8}=\frac{9x8+3}{8}=\frac{72+3}{8}=\frac{75}{8}\)

\(12\frac{7}{10}=\frac{12x10+7}{10}=\frac{120+7}{10}=\frac{127}{10}\)

\(2\frac{3}{5}=\frac{13}{5}\)

\(5\frac{4}{9}=\frac{49}{9}\)

\(9\frac{3}{8}=\frac{75}{8}\)

\(12\frac{7}{10}=\frac{127}{10}\)

Tổng của 9 số tự nhiên đầu là:

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

Vậy phân số đó là: \(\frac{45}{10}\)= \(\frac{9}{2}\)

tk nhé

hãy tính tổng sau:

1 / 10 + 2 / 10 + 3 / 10 + ....+ 8 / 10 + 9 / 10 

Tử số :

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

Vậy phân số đó là: 45 / 10 = 9 / 2 

nhé !

Tổng của 9 số tự nhiên đầu tiên là:

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

Vậy ta có phân số: \(\frac{45}{10}\)= \(\frac{9}{2}\)

tk nhé

\(\frac{1}{10}+\frac{2}{10}+\frac{3}{10}+....+\frac{8}{10}+\frac{9}{10}\)

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

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

\(=\frac{10+10+10+10+5}{10}\)

\(=\frac{45}{10}=\frac{9}{2}\)

k mk nha

A. >

B . <

C. > 

D. =

hok tốt

a.>

b.<

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d.=

1 nha

chúc bạn học tốt

click cho mình xin 1 điểm hỏi đáp

ok

\(\frac{1}{2}\)x \(\frac{9}{10}\)+ \(\frac{8}{10}\)+ \(\frac{2}{4}\)+ \(\frac{3}{10}\)x \(0,5\)

= \(0,5\)x \(0,9\)+ \(0,8\)+ \(0,5\)x \(0,5\)

\(=0,45\)x \(1,3\)x \(0,5\)

\(=0,45\)x \(0,65=0,2925\)