1. 3x - 17 = x+3
3x - x = 3 + 17
2x = 20
x = 20 :2
x = 10
2. |x-3| - 12 = |-5|
|x-3| -12 = 5
|x-3| = 5 + 12
|x-3| = 17
=> x-3 = +17 , -17
x - 3 = 17x = 17 + 3
x = 20
x - 3 = -17x = -17 + 3
x = -14
3 . 25 - ( x -5 ) = -415 -( 15 -415)
25 - x +5 = -415 - 15 +415
25 - x +5 = ( -415 + 415) -15
25 - x +5 = 0-5 = -5
25 - x = -5-5
25 - x = -10
x = 25 - -10
x = 35
4. ( x -3 ) . ( 2x +6 ) = 0
=> x-3 = 0 hoặc 2x +6 = 0
x - 3 = 0x = 0 + 3 = 3
2x +6 = 02x = 0-6=-6
x = -6 : 2
x = -3
\(1;3x-17=x+3\)
\(\Leftrightarrow3x-x=3+17\)
\(\Leftrightarrow2x=20\)
\(\Rightarrow x=10\)
\(2;\left|x-3\right|-12=\left|-5\right|\)
\(\Leftrightarrow\left|x-3\right|-12=5\)
\(\Leftrightarrow\left|x-3\right|=5+12\)
\(\Leftrightarrow\left|x-3\right|=17\)
\(\Rightarrow\orbr{\begin{cases}x-3=17\\3-x=17\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=17+3\\-x=17-3\end{cases}\Leftrightarrow\orbr{\begin{cases}x=20\\x=-14\end{cases}}}\)
\(3;25-\left(x-5\right)=-415-\left(15-415\right)\)
\(\Leftrightarrow25-x+5=-415-15+415\)
\(\Leftrightarrow-x=-415-15+415-25-5\)
\(\Leftrightarrow-x=-45\)
\(\Rightarrow x=45\)
\(4;\left(x-3\right)\left(2x+6\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x-3=0\\2x+6=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=3\\x=-3\end{cases}}}\)
3x-17=x+3
3x-x=3+17
2x=20
x=10
lx-3l - 12 = l-5l = 5
lx-3l = 5+12=17
<=>\(\orbr{\begin{cases}x-3=17\\x-3=-17\end{cases}\Leftrightarrow\orbr{\begin{cases}x=20\\x=-14\end{cases}}}\)