1) \(\left(x-2\right)\left(x+4\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x-2=0\\x+4=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=2\\x=-4\end{matrix}\right.\)
2) \(\left(x-2\right)\left(x+15\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x-2=0\\x+15=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=2\\x=-15\end{matrix}\right.\)
3) \(\left(7-x\right)\left(x+19\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}7-x=0\\x+19=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=7\\x=-19\end{matrix}\right.\)
4) \(-5< x< 1\)
\(\Rightarrow x\in\left\{-1;-3;-2;-1;0\right\}\)
5) \(\left(x-3\right)\left(x-5\right)< 0\)
\(\Rightarrow\left[{}\begin{matrix}x-3>0\\x-5< 0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x>3\\x< 5\end{matrix}\right.\)
\(\Rightarrow3< x< 5\)
6) \(2x^2-3=29\)
\(\Rightarrow2x^2=29+3\)
\(\Rightarrow2x^2=32\)
\(\Rightarrow x^2=\dfrac{32}{2}\)
\(\Rightarrow x^2=16\)
\(\Rightarrow x^2=4^2\)
\(\Rightarrow\left[{}\begin{matrix}x=4\\x=-4\end{matrix}\right.\)
7) \(-6x-\left(-7\right)=25\)
\(\Rightarrow-6x+7=25\)
\(\Rightarrow-6x=25-7\)
\(\Rightarrow-6x=18\)
\(\Rightarrow x=\dfrac{18}{-6}\)
\(\Rightarrow x=-3\)
8) \(46-\left(x-11\right)=-48\)
\(\Rightarrow x-11=48+46\)
\(\Rightarrow x-11=94\)
\(\Rightarrow x=94+11\)
\(\Rightarrow x=105\)
1: (x-2)(x+4)=0
=>x-2=0 hoặc x+4=0
=>x=2 hoặc x=-4
2: (x-2)(x+15)=0
=>x-2=0 hoặc x+15=0
=>x=2 hoặc x=-15
3: (7-x)(x+19)=0
=>7-x=0 hoặc x+19=0
=>x=7 hoặc x=-19
4: -5<x<1
=>\(x\in\left\{-4;-3;-2;-1;0\right\}\)
5: (x-3)(x-5)<0
=>x-3>0 và x-5<0
=>3<x<5
6: 2x^2-3=29
=>2x^2=32
=>x^2=16
=>x=4 hoặc x=-4
7: -6x-(-7)=25
=>-6x=25-7=18
=>x=-3
8: 46-(x-11)=-48
=>x-11=46+48=94
=>x=94+11=105
