ab200

\(\left|x\right|\ge0\)

\(\Rightarrow\frac{-1}{\left|x\right|+1}\ge\frac{-1}{0+1}=-1\)

Dấu bằng khi x = 0

\(\frac{9^5.27^3}{3^{18}}\)

\(=\frac{\left(3^2\right)^5.\left(3^3\right)^3}{3^{18}}\)

\(=\frac{3^{10}.3^9}{3^{18}}\)

\(=\frac{3^{19}}{3^{18}}=3\)

9 mũ 5 với 27 mũ 3 nhé

b) \(1,6-\left|x-0,2\right|=0\)

\(\Leftrightarrow\left|x-0,2\right|=1,6\)

\(\Leftrightarrow\orbr{\begin{cases}x-0,2=1,6\\x-0,2=-1,6\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=1,8\\x=-1,4\end{cases}}\)

a) \(\frac{-7}{15}.\frac{5}{8}.\frac{15}{-7}.\left(-32\right)\)

\(=\frac{5}{8}.\left(-32\right)\)

\(=-20\)

1 + 1 = 2

@Cỏ

#Forever

1+1=2 nha bạn!

\(\frac{2}{x}=\frac{-5}{3}\)

\(\Rightarrow x=\frac{3}{-5}.2\)

\(\Rightarrow x=\frac{6}{-5}\)

Vậy chọn B

\(\frac{x+1}{3}=\frac{y+2}{4}=\frac{z-1}{5}\)

Áp dụng tính chất dãy tỉ số bằng nhau ta có: 

\(\frac{x+1}{3}=\frac{y+2}{4}=\frac{z-1}{5}=\frac{\left(x+1\right)+\left(y+2\right)-3\left(z-1\right)}{3+4-3.5}=\frac{56}{-8}=-7\)

\(\Leftrightarrow\hept{\begin{cases}x+1=-7.3=-21\\y+2=-7.4=-28\\z-1=-7.5=-35\end{cases}}\Leftrightarrow\hept{\begin{cases}x=-22\\y=-30\\z=-34\end{cases}}\)