\(x+\left(13-15\right)=5+\left(10-7\right)\)

\(< =>x-2=8=>x=10\)

Ta có: \(x+\left(13-15\right)=5+10-7\)

\(\Leftrightarrow x-2=15-7=8\)

hay x=10

x + (13 - 15) = 5 + (10 - 7)

x + (13 - 15) = 5 + 3

x + (13 - 15) = 8

x + (-2) = 8

x = 8 - (-2)

x = 10

Chúc bạn học tốt!

\(a,\Rightarrow x=\dfrac{7}{3}+\dfrac{6}{7}=\dfrac{49+18}{21}=\dfrac{67}{21}\\ b,\Rightarrow x=\dfrac{15}{7}-\dfrac{13}{14}=\dfrac{30-13}{14}=\dfrac{17}{14}\\ c,\Rightarrow3x=\dfrac{9}{4}-\dfrac{5}{6}=\dfrac{27-10}{12}=\dfrac{17}{12}\\ \Rightarrow x=\dfrac{17}{12}\cdot\dfrac{1}{3}=\dfrac{17}{36}\)

\(x=\dfrac{7}{3}+\dfrac{6}{7}=\dfrac{67}{21}\)

\(x=\dfrac{15}{7}-\dfrac{13}{14}=\dfrac{17}{14}\)

\(x=\left(\dfrac{9}{4}-\dfrac{5}{6}\right):3=\dfrac{17}{36}\)

\(x-\dfrac{6}{7}=\dfrac{7}{3}\\ \Rightarrow x=\dfrac{7}{3}+\dfrac{6}{7}\\ \Rightarrow x=\dfrac{67}{21}\)

\(x+\dfrac{13}{14}=\dfrac{15}{7}\\ \Rightarrow x=\dfrac{15}{7}-\dfrac{13}{14}\\ \Rightarrow x=\dfrac{17}{14}\)

\(\dfrac{9}{4}-3\times x=\dfrac{5}{6}\\ \Rightarrow3\times x=\dfrac{9}{4}-\dfrac{5}{6}\\ \Rightarrow3\times x=\dfrac{17}{12}\\ \Rightarrow x=\dfrac{17}{12}:3\\ \Rightarrow x=\dfrac{17}{36}\)

Bài 1: 

Ta có: \(x-35\%\cdot x=\dfrac{1}{25}\)

\(\Leftrightarrow65\%\cdot x=\dfrac{1}{25}\)

\(\Leftrightarrow x=\dfrac{1}{25}:\dfrac{13}{20}=\dfrac{1}{25}\cdot\dfrac{20}{13}=\dfrac{4}{65}\)

Vậy: \(x=\dfrac{4}{65}\)

Bài 2: 

a) Ta có: \(17\dfrac{2}{31}-\left(\dfrac{15}{17}+6\dfrac{2}{31}\right)\)

\(=17\dfrac{2}{31}-\dfrac{15}{17}-6\dfrac{2}{31}\)

\(=11+\dfrac{2}{31}-\dfrac{15}{17}\)

\(=\dfrac{5366}{527}\)

bn l-ike cho mk trước đã

Ta có : A=20/11×13 + 20/13×15 +20/15×17+...+20/53×55

A = 10 ×( 2/11×13+2/13×15+...12/53×55)

A = 10 ×(1/11-1/13+1/13-1/15+1/15-1/17+...+1/53-1/55)

A = 10 × (1/11-1/55)

A =10 × 4/55

A = 8/11

\(\dfrac{x}{12}=x+\dfrac{15}{16}\)

\(\Leftrightarrow\dfrac{x}{12}=\dfrac{16x+15}{16}\)

\(\Rightarrow12\left(16x+15\right)=16x\)

\(\Leftrightarrow192x+180=16x\)

\(\Leftrightarrow176x=-180\)

\(\Leftrightarrow x=-\dfrac{45}{44}\)

Vậy \(x=-\dfrac{45}{44}\)

\(\dfrac{x}{12}=\dfrac{x+15}{16}\)

\(\Rightarrow12\left(x+15\right)=16x\)

\(\Leftrightarrow12x+180=16x\)

\(\Leftrightarrow4x=180\)

\(\Leftrightarrow x=45\)

Vậy x = 45

\(\dfrac{x}{12}=\dfrac{x+15}{16}\)

\(16x=12\left(x+15\right)\)

\(16x=12x+180\)

\(4x=180\)

\(x=45\)

\(3x+15=141\\ 3x=126\\ x=42\)

\(x+x+x+15=141\)

\(3x=141-15\)

\(3x=126\)

\(x=42\)

\(\text{x+x+x+15=141}\)

\(3x+15=141\)

\(3x=141-15\)

\(3x=126\)

  \(x=126\div3\)

  \(x=42\)

a) x = 3

b) x = 3

c) x = 1

d) x = 23

Bạn ghi lại đề đi bạn

\(x=\dfrac{15}{13}+\dfrac{11}{13}=\dfrac{15+11}{13}=\dfrac{26}{13}\)

\(x=\dfrac{15}{13}+\dfrac{11}{13}\\ x=\dfrac{26}{13}\)

X = 11/13 + 15/13 = 26/13

zậy thoyy???

đề=hỏi chấm