\(\frac{-72}{14}=\frac{-36}{7}\)

\(\frac{990}{2610}=\frac{11}{29}\)

\(\frac{374}{506}=\frac{17}{23}\)

\(\frac{3600-75}{8400-175}=\frac{3525}{8225}=\frac{3}{7}\)

hok tốt!!

a) Ta có : 

990 = 2.3².5.11

2610=2.3².5.29

ƯCLN(990;2610) = 2.3².5=90

\(\Rightarrow\frac{990}{2610}=\frac{990:90}{2610:90}=\frac{11}{29}\)

Tương tự với câu b) 

\(a,\frac{990}{2610}=\frac{990:90}{2610:90}=\frac{11}{29}\)

\(b,\frac{374}{506}=\frac{374:2}{506:2}=\frac{187}{253}=\frac{187:11}{253:11}=\frac{17}{23}\)

\(c,\frac{3600-75}{8400-175}=\frac{3525}{8225}=\frac{3525:25}{8225:25}=\frac{141}{329}\)

\(d,\frac{9^{14}.25^5.8^7}{18^{12}.625^3.24^3}=\frac{9^{12}.9^2.25^3.25^2.8^3.8^4}{\left(9.2\right)^{12}.\left(25.25\right)^3.\left(8.3\right)^3}=\frac{9^{12}.9^2.25^3.25^2.8^3.8^3.8}{9^{12}.2^{12}.25^3.25^2.25.8^3.3^3}=\frac{9^2.8}{2^{12}.25.3^3}\) đến đây bn tự làm nốt đi! 

~ mỏi ~

lấy bài của chị đúng ko em

\(\frac{990}{2610}=\frac{990:11}{2610:11}=\frac{11}{29}\)

\(\frac{374}{506}=\frac{374:22}{506:22}=\frac{17}{23}\)

\(\frac{3600-75}{8400-175}=\frac{3525}{8225}=\frac{3525:1175}{8225:1175}=\frac{3}{7}\)

\(\frac{9^{14}.255^5.8^7}{18^{12}.625^3.24^3}=\frac{3^{28}.5^5.3^5.17^5.2^{21}}{2^{12}.3^{24}.5^{12}.2^9.3^3}=\frac{3^{33}.5^5.17^5.2^{21}}{2^{21}.3^{27}.5^{12}}=\frac{3^6.17^5}{5^7}\)

Máy tính đâu

374         187                               3737             37

____    = _____                           ______     = _____

506         253                              5656             56

dễ lắm mà

ừa, nhưng mik còn những câu sau khó hơn nhưng mỏi tay quá nên tí gửi tiếp!

a,=-36/7

b,=11/29

c,=17/23

d,=3/7

e,=-5/9

\(\frac{1}{87}\)

\(\frac{7}{9.87-2.87}\)=  \(\frac{7}{\left(9-2\right).87}\)=\(\frac{7}{7.87}\)= \(\frac{1}{87}\)

3/2

1/3

3/2

1/3

\(\dfrac{12}{8}=\dfrac{12\div4}{8\div4}=\dfrac{3}{2};\dfrac{7}{21}=\dfrac{7\div7}{21\div7}=\dfrac{1}{3}\)