`1,(2x+1)(x-1)=0`
\(\Leftrightarrow\left[{}\begin{matrix}2x+1=0\\x-1=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}2x=-1\\x=1\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x=1\end{matrix}\right.\)
`2, (3x+5)(4x-12)=0`
\(\Leftrightarrow\left[{}\begin{matrix}3x+5=0\\4x-12=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}3x=-5\\4x=12\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{5}{3}\\x=3\end{matrix}\right.\)
`3,(3x-1)(2x-3)(x+5)=0`
\(\Leftrightarrow\left[{}\begin{matrix}3x-1=0\\2x-3=0\\x+5=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}3x=1\\2x=3\\x=-5\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{3}\\x=\dfrac{3}{2}\\x=-5\end{matrix}\right.\)
`4,(2-3x)(2x^2+1)=0`
\(\Leftrightarrow\left[{}\begin{matrix}2-3x=0\\2x^2+1=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}2=3x\\2x^2=-1\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\x\in\varnothing\end{matrix}\right.\)
`5, x^2-x=0`
`<=>x(x-1)=0`
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x-1=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=1\end{matrix}\right.\)
`6, x^2-2x=0`
`<=>x(x-2)=0`
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x-2=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=2\end{matrix}\right.\)
7 =>(x+1)(x+2)-(2-x)(x+2)=0
=>(x+2)(x+1-2+x)=0
=>(x+2)(2x-1)=0
=>x=1/2 hoặc x=-2
8: =>(2x-3)(3x-4)-(2x-3)(x-1)=0
=>(2x-3)(3x-4-x+1)=0
=>(2x-3)(2x-3)=0
=>x=3/2
9: =>x^2-2-3x^2+7x+6x-14=0
=>-2x^2+13x-16=0
=>2x^2-13x+16=0
Δ=(-13)^2-4*2*16=169-128=41>0
=>PT có 2 nghiệm pb là:
\(\left\{{}\begin{matrix}x=\dfrac{13-\sqrt{41}}{4}\\x=\dfrac{13+\sqrt{41}}{4}\end{matrix}\right.\)
10: =>(x-3)(3x-2)=0
=>x=2/3 hoặc x=3
11: =>(x-2)(8x-1)=0
=>x=1/8 hoặc x=2
12: =>(2x-3)(5x+2)=0
=>x=-2/5 hoặc x=3/2
13: =>(x-5)(5-2x)=0
=>x=5/2 hoặc x=5
14: =>x(x-3)=0
=>x=0 hoặc x=3
