Gợi ý: Rút gọn 2 ps, quy đồng rồi so sánh.

15/50 ? 90/45 ra 0.26<2

a)70=2*5*7

=>2*3*5/70=3/7

b)33*4=11*3*2*2=11*6*2

=>2*6*11/33*4=1

c)21*45=9*5*3*7

=>21*45/3*5*7*9=1

\(\frac{2\times3\times5}{70}\)

= \(\frac{2\times3\times5}{7\times2\times5}\)

= \(\frac{3}{7}\)

=1 nha

bằng 1 nhé bạn

a)\(\dfrac{5}{7}+\dfrac{4}{9}=\dfrac{45}{63}+\dfrac{28}{63}=\dfrac{73}{63}\) ; \(\dfrac{9}{11}+\dfrac{3}{8}=\dfrac{72}{88}+\dfrac{33}{88}=\dfrac{105}{88}\)

\(\dfrac{4}{5}-\dfrac{2}{3}=\dfrac{12}{15}-\dfrac{10}{15}=\dfrac{2}{15}\); \(\dfrac{16}{25}-\dfrac{2}{5}=\dfrac{16}{25}-\dfrac{10}{25}=\dfrac{6}{25}\)

b)\(5+\dfrac{3}{5}=\dfrac{25}{5}+\dfrac{3}{5}=\dfrac{28}{5};10-\dfrac{9}{16}=\dfrac{160}{16}-\dfrac{9}{16}=\dfrac{151}{16}\)

\(\dfrac{2}{3}-\left(\dfrac{1}{6}+\dfrac{1}{8}\right)=\dfrac{2}{3}-\left(\dfrac{8}{48}+\dfrac{6}{48}\right)=\dfrac{2}{3}-\dfrac{14}{48}=\dfrac{32}{48}-\dfrac{14}{48}=\dfrac{3}{8}\)

4/9 + 11/8 - 5/6 = 32/72 + 99/72 - 60/72 = 32+99-60/72 = 71/72

Ai ngang qua xin để lại 1 l-i-k-e

Sau khi điều tra, trắng đã đưa ra kết quả 

4/9 + 11/8 - 5/6

= 32/72 + 99/72 - 60/72 

= 131/72 - 60/72

= 71/72

a Đ

b S

c S

d Đ

a ) S 

b ) Đ

c ) S

d ) Đ

k cho mk nhé 

\(\frac{1}{11}+\frac{2}{11}+\frac{3}{11}+\frac{4}{11}+\frac{5}{11}+\frac{6}{11}+\frac{7}{11}+\frac{8}{11}+\frac{9}{11}+\frac{10}{11}\)

\(=\frac{1+2+3+4+5+6+7+8+9+10}{11}\)

\(=\frac{\left(1+10\right)+\left(2+9\right)+\left(3+8\right)+\left(4+7\right)+\left(5+6\right)}{11}\)

\(=\frac{11+11+11+11+11}{11}\)

\(=\frac{11\cdot5}{11}=5\)

\(= \frac{1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10}{11}\)

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

Vậy là bằng 55/11 nhé bạn

\(a.\left(\frac{6}{11}+\frac{5}{11}\right).\frac{3}{7}=1\cdot\frac{3}{7}=\frac{3}{7}b.\frac{3}{5}\cdot\frac{7}{9}+\frac{3}{5}\cdot\frac{2}{9}=\frac{3}{5}\cdot\left(\frac{7}{9}+\frac{2}{9}\right)=\frac{3}{5}\cdot1=\frac{3}{5}\)

= 1192 nhé

 hok tốt

:D