trình bày cho 5 sao a,x ²-3/5x=0 b,(2/7x-1/2)-(3/14-5)-(1-2/21x)=2

Đáp án+Giải thích các bước giải:

`a, x^2-3/5x=0`

`<=> x(x-3/5)=0`

`<=> [(x=0),(x-3/5=0):}`

`<=> [(x=0),(x=3/5):}`

Vậy `x \in {0;3/5}`

`b, (2/7 x-1/2)-(3/14-5)-(1-2/21 x)=2`

`<=> 2/7 x-1/2-3/14+5-1+2/21x=2`

`<=> (2/7 x+2/21x)-(1/2+3/14-5+1)=2`

`<=> 8/21 x-(-23/7)=2`

`<=> 8/21x+23/7=2`

`<=> 8/21x=2-23/7`

`<=> 8/21x=-9/7`

`<=> x=(-9/7) : 8/21`

`<=> x=-9/7 . 21/8`

`<=> x=-27/8`

Vậy `x=-27/8` 

 `a)x^2-3/5x=0`

`⇒x(x-3/5)=0`

⇒\(\left[ \begin{array}{l}x=0\\x-\frac{3}{5}=0\end{array} \right.\)

⇒\(\left[ \begin{array}{l}x=0\\x=\frac{3}{5}\end{array} \right.\)

Vậy `x={0;3/5}`

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  `b)(2/7x-1/2)-(3/14-5)-(1-2/21x)=2`

`⇒2/7x-1/2-3/14+5-1+2/21x=2`

`⇒2/7x+2/21x=2+1/2+3/14-5+1`

`⇒(2/7+2/21)x=1/2+3/14-2`

`⇒8/21x=(-9)/7`

`⇒x=(-9)/7:8/21`

`⇒x=(-27)/8`

Vậy `x=(-27)/8`