a) | x + 2 | = 0

=> x + 2 = 0

=> x = -2

b) | x - 5 | = | -7 |

=> | x - 5 | = 7

\(\Rightarrow\orbr{\begin{cases}x-5=7\\x-5=-7\end{cases}}\Rightarrow\orbr{\begin{cases}x=12\\x=-2\end{cases}}\)

2.(x+1)=x+9
<=> 2x + 2 - x - 9 = 0
<=> x = 7

 chắc vậy đó em nếu đúng cho a 1 k nha

Đáp án

450 số

Đúng thì k ko đúng thì hoy okkk

đáp án

(999-101):2+1=450

Vậy có 450 số tự nhiên lẻ có 3 chữ số

d) ( x : 3 - 4 ) . 5 = 15

=> x : 3 - 4 = 15 : 5 = 3

=> x : 3 = 3 + 4 = 7

=> x = 7 . 3 =  21

a) | x + 2 | = 0

=> x + 2 = 0

=> x = -2

\(\frac{\frac{4}{5}+\frac{4}{7}-\frac{4}{11}-\frac{4}{13}}{\frac{6}{5}+\frac{6}{7}-\frac{6}{11}-\frac{6}{13}}=\frac{4\left(\frac{1}{5}+\frac{1}{7}-\frac{1}{11}-\frac{1}{13}\right)}{6\left(\frac{1}{5}+\frac{1}{7}-\frac{1}{11}-\frac{1}{13}\right)}=\frac{4}{6}=\frac{2}{3}\)

\(=\frac{4\left(\frac{1}{5}+\frac{1}{7}-\frac{1}{11}-\frac{1}{13}\right)}{6\left(\frac{1}{5}+\frac{1}{7}-\frac{1}{11}-\frac{1}{13}\right)}\)

\(=\frac{4}{6}\)

\(=\frac{2}{3}\)

a)\(-\frac{3}{4}x+\frac{1}{6}x=1-2\frac{5}{9}\)

\(\Leftrightarrow-\frac{7}{12}x=-\frac{14}{9}\)

\(\Leftrightarrow x=\frac{8}{3}\)

b)\(\left|2n-\frac{3}{8}\right|+2\frac{3}{4}=3\frac{1}{16}\)

\(\Leftrightarrow\left|2n-\frac{3}{8}\right|=\frac{5}{16}\)

\(\Leftrightarrow\orbr{\begin{cases}2n-\frac{3}{8}=\frac{5}{16}\\2n-\frac{3}{8}=-\frac{5}{16}\end{cases}\Leftrightarrow\orbr{\begin{cases}2n=\frac{11}{16}\\2n=\frac{1}{16}\end{cases}\Leftrightarrow}}\orbr{\begin{cases}x=\frac{11}{32}\\x=\frac{1}{32}\end{cases}}\)

c)\(\left(x-\frac{1}{5}\right)^2+1\frac{9}{25}=2\)

\(\Leftrightarrow\left(x-\frac{1}{5}\right)^2=\frac{16}{25}\)

\(\Leftrightarrow\orbr{\begin{cases}x-\frac{1}{5}=\frac{4}{5}\\x-\frac{1}{5}=-\frac{4}{5}\end{cases}\Leftrightarrow\orbr{\begin{cases}x=1\\x=-\frac{3}{5}\end{cases}}}\)

#H