Question

tim x \(\in\)Q biet \(|\)x-2.1\(|\)-0.9=0

Answer 1

\(\left|x-2.1\right|-0.9=0\)

\(\left|x-2.1\right|=0.9\)

TH1 : \(x-2.1=0.9\)

\(x=3\)

Th2 : \(x-2.1=-0.9\)

\(x=1.2\)

Answer 2

\(\left|x-2,1\right|-0,9=0\)

\(\Leftrightarrow\left|x-2,1\right|=0,9\)

\(\Rightarrow x-2,1=\orbr{\begin{cases}0,9\\-0,9\end{cases}}\)

\(\Rightarrow x=\orbr{\begin{cases}3\\1,2\end{cases}}\)

Answer 3

Ta có : |x - 2.1| - 0.9 = 0

=> |x - 2.1| = 0.9

\(\Rightarrow\orbr{\begin{cases}x-2.1=0.9\\x-2.1=-0.9\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=3\\x=1.2\end{cases}}\)