(4x ² -x) (x ²+3x-4) =0 (x ²+2x) (x ²+x-2)=0

Đáp án+Giải thích các bước giải:

`(4x^2 -x) (x^2+3x-4) =0`
`<=>x(4x -1) (x^2+4x-x-4) =0`
`<=>x(4x -1) [x(x+4)-(x+4)] =0`
`<=>x(4x -1) (x-1)(x+4) =0`
`<=>`\(\left[ \begin{array}{l}x=0\\4x -1=0\\x-1=0\\x+4=0\end{array} \right.\) 
`<=>`\(\left[ \begin{array}{l}x=0\\4x =1\\x=1\\x=-4\end{array} \right.\) 

`<=>`\(\left[ \begin{array}{l}x=0\\x =\dfrac{1}{4}\\x=1\\x=-4\end{array} \right.\) 

Vậy `S={0;1/4;1;-4}`

`(x^2+2x) (x^2+x-2)=0`
`<=>(x^2+2x) (x^2+2x-x-2)=0`
`<=>x(x+2) [x(x+2)-(x+2)]=0`
`<=>x(x+2)(x-1)(x+2)=0`
`<=>x(x+2)^2(x-1)=0`
`<=>`\(\left[ \begin{array}{l}x=0\\x+2=0\\x-1=0\end{array} \right.\) 
`<=>`\(\left[ \begin{array}{l}x=0\\x=-2\\x=1\end{array} \right.\) 

Vậy `S={0;-2;1}`