\(\frac{2x-5}{y+1}=\frac{x-1}{3y}=\frac{1}{3}\Rightarrow\hept{\begin{cases}3\left(2x-5\right)=y+1\\x-1=y\end{cases}}\)

\(\Rightarrow6x-15=x-1+1\)

\(\Leftrightarrow x=3\)

suy ra \(y=2\). 

đề bài sai nha

BC=BC

suy ra ABC=ADC

vì ABC DÀI  BẰNG ADC

1) \(\sqrt{25-9}=\sqrt{16}\) \(=\pm4\)

2) \(\sqrt{0,01}-\sqrt{0,25}\)

\(=\sqrt{\frac{1}{100}}-\sqrt{\frac{25}{100}}\)

\(=\frac{1}{10}-\frac{5}{10}\)

\(=\frac{-4}{10}\)

3)\(\left(\sqrt{\frac{4}{9}}+\sqrt{\frac{25}{144}}-\sqrt{\frac{49}{81}}\right):\sqrt{\frac{121}{36}}\)

\(=\left(\frac{\text{2}}{3}+\frac{5}{12}-\frac{7}{9}\right):\frac{11}{6}\)

\(=\frac{11}{36}:\frac{11}{6}=\frac{1}{6}\)

\(\sqrt{\frac{1}{9}+\frac{1}{16}}\)

\(=\frac{1}{3}+\frac{1}{4}\)

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

\(\sqrt{4+36+81}\)

\(=\sqrt{121}\)

\(=\pm11\)

a ) \(6,3+\left(-3,7\right)+2,4+\left(-0,3\right)=8,7-4=4,7\)

b) \(\left(-4,9\right)+5,5+4,9+\left(-5,5\right)=0\)

c) \(2,9+3,7+\left(-4,2\right)+\left(-2,9\right)+4,2=3,7\)

d) \(\left(-6,5\right).2,8+2,8.\left(-3,5\right)=2,8\left(-10\right)=-28\)

chơi free fire ko

\(\hept{\begin{cases}\frac{x}{2}=\frac{y}{3}\Leftrightarrow\frac{x}{10}=\frac{y}{15}\\\frac{z}{4}=\frac{y}{5}\Leftrightarrow\frac{z}{12}=\frac{y}{15}\end{cases}\Leftrightarrow\frac{x}{10}=\frac{y}{15}=\frac{z}{12};x+y-z=-39}\)

Tính chất dãy tỉ số bằng nhau:

\(\frac{x}{10}=\frac{y}{15}=\frac{z}{12}=\frac{x+y-z}{10+15-12}=-\frac{39}{13}=-3\)

\(\Rightarrow\hept{\begin{cases}\frac{x}{10}=-3\Leftrightarrow x=-30\\\frac{y}{15}=-3\Leftrightarrow y=-45\\\frac{z}{12}=-3\Leftrightarrow z=-36\end{cases}}\)

Bằng - 45