`e)2x^3-4x^2=0`

`<=>2x^2(x-2)=0`

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

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

Vậy `x=0` hoặc `x=2`

`f)4x^4-x^2=0`

`<=>x^2(4x^2-1)=0`

`<=>x^2(2x-1)(2x+1)=0`

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

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

Vậy: `x=0` hoặc `x=1/2` hoặc `x=-1/2`

`g)(x-1)^2=(2x+1)^2`

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

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

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

Vậy: `x=-2` hoặc `x=0`

`h)x^2-25+(4-x)(x+5)=0`

`<=>(x-5)(x+5)+(4-x)(x+5)=0`

`<=>(x+5)(x-5+4-x)=0`

`<=>-(x+5)=0`

`<=>x+5=0`

`<=>x=-5`

Vậy: `x=-5`

Đáp án `+` Giải thích các bước giải `!`

`to` Tìm `x:`

`e)`

`2x^3-4x^2 = 0`

`<=> 2x^2(x-2) = 0`

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

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

Vậy `S= {0; 2}`

`f)`

`4x^4-x^2 = 0`

`<=> x^2(4x^2-1) = 0`

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

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

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

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

Vậy `S= {0; 1/2; -1/2}`

`g)`

`(x-1)^2 = (2x+1)^2`

`<=> (x-1)^2-(2x+1)^2 = 0`

`<=> (x-1-2x-1)(x-1+2x+1) = 0`

`<=> 3x(-x-2) = 0`

`<=> -3x(x+2) = 0`

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

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

Vậy `S= {0; -2}`

Áp dụng: `a^2-b^2 = (a-b)(a+b)`

`h)`

`x^2-25+(4-x)(x+5) = 0`

`<=> (x^2-25)+(4-x)(x+5) = 0`

`<=> (x+5)(x-5)+(4-x)(x+5) = 0`

`<=> (x+5)(x-5+4-x) = 0`

`<=> -1(x+5) = 0`

`<=> x+5 = 0`

`<=> x = -5`

Vậy `S= {-5}`

Áp dụng: `a^2-b^2 = (a-b)(a+b)`