a. \(\left(x-3\right)\left(x+4\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x-3=0\\x+4=0\end{cases}\Rightarrow\orbr{\begin{cases}x=3\\x=-4\end{cases}}}\)
\(\Rightarrow x\in\left\{-4;3\right\}\)
b. \(\left(x-2\right)\left(5-x\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x-2=0\\5-x=0\end{cases}\Rightarrow\orbr{\begin{cases}x=2\\x=5\end{cases}}}\)
\(\Rightarrow x\in\left\{2;5\right\}\)
c. \(x\left(x+1\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x=0\\x+1=0\end{cases}\Rightarrow\orbr{\begin{cases}x=0\\x=-1\end{cases}}}\)
\(\Rightarrow x\in\left\{-1;0\right\}\)
d. \(\left|2x-5\right|=13\)
\(\Rightarrow\orbr{\begin{cases}2x-5=13\\2x-5=-13\end{cases}\Rightarrow\orbr{\begin{cases}2x=18\\2x=-8\end{cases}\Rightarrow}\orbr{\begin{cases}x=9\\x=-4\end{cases}}}\)
\(\Rightarrow x\in\left\{-4;9\right\}\)
e. Đề bài : -12= |x-9|= 3 ???
f. \(11-\left(15-\left|x\right|\right)=1\)
\(15-\left|x\right|=10\)
\(\left|x\right|=5\)
\(\Rightarrow x\in\left\{-5;5\right\}\)
a. ( x- 3) .( x+4 ) =0
* x-3=0 * x+4=0
x=0+3 x=0-4
x=3 x=-4
vậy x=3 hoặc x=-4
b. ( x -2 ). (5-x ) =0
* x-2=0 * 5-x=0
x=0+2 x=5-0
x=2 x=5
vậy x=2 hoặc x=5
c. x. (x+1 ) =0
* x=0 * x+1=0
x=0-1
x=-1
vậy x=0 hoặc x=-1
d.|2x - 5| =13
* 2x-5=13 * 2x-5=-13
2x=3+15 2x=-13+5
2x=18 2x=-8
x=18:2 x=-8:2
x=9 x=-4
vậy x=9 hoặc x=-4
e.-12 =| x - 9 | = 3 (sai đề)
f. 11-(15 - | x | ) = 1
15-|x|=11-1
15-|x|=10
|x|=15-10
|x|=5
=>x=5 hoặc x=-5
vậy x=5 hoặc x=-5
