a) \(\dfrac{2}{5}=\dfrac{2\times3}{5\times3}=\dfrac{6}{15}=\dfrac{2}{5}\)

\(\dfrac{4}{7}=\dfrac{4\times2}{7\times2}=\dfrac{8}{14}=\dfrac{4}{7}\)

\(\dfrac{13}{54}=\dfrac{13\times3}{54\times3}=\dfrac{39}{162}=\dfrac{13}{54}\) 

b) \(\dfrac{8}{20}=\dfrac{8:4}{20:4}=\dfrac{2}{5}\)

\(\dfrac{10}{16}=\dfrac{10:2}{16:2}=\dfrac{5}{8}\)

\(\dfrac{25}{65}=\dfrac{25:5}{65:5}=\dfrac{5}{13}\)

\(Sửa:\dfrac{17}{13}+\dfrac{61}{115}-\dfrac{4}{13}+\dfrac{54}{115}+\dfrac{2004}{2005}\\ =\left(\dfrac{17}{13}-\dfrac{4}{13}\right)+\left(\dfrac{61}{115}+\dfrac{54}{115}\right)+\dfrac{2004}{2005}\\ =1+1+\dfrac{2004}{2005}=\dfrac{6014}{2005}\)

de bai sia

1222000

1222000

chúc bn học tốt

1222000

1222+2222=3444

tích mk nha bn

1222+2222

= 3444

1222+2222=3444

y - 27/54 - 1212/3636 = 1/6

y - 1/2 - 1/3 = 1/6

y = 1/6 + 1/2 + 1/3

y = 1

2444 nha bạn

Nhớ k cho mình nha 

Chúc các bạn học giỏi

=2444 tích nha

1222 x 2=1222+1222=2444

\(\Leftrightarrow x^3=-4\cdot54=-216=\left(-6\right)^3\\ \Leftrightarrow x=-6\)

\(\Leftrightarrow x^3=-216\\ \Leftrightarrow x=-6\)

x³ = 54.(-4) = -216

x³ = (-6)³

Vậy x = -6