Question

1) 2x ( 3x- 1/2) - x ( 6x - 11 ) = 30x

2) x ( 7 - 4x ) + 2x ( 2x - 1 ) = 24

3) 1/2 (x^2 - 2x) - x ( 1/2x +3) = 1/2

4) x(x - 1) - x ( x + 1 ) -1/3x = 1/4x

Answer 1

1: \(\Leftrightarrow6x^2-x-6x^2+11x-30x=0\)

=>-20x=0

hay x=0

2: \(\Rightarrow7x-4x^2+4x^2-2x=24\)

=>5x=24

hay x=24/5

3: \(\Leftrightarrow x^2\cdot\dfrac{1}{2}-x-\dfrac{1}{2}x^2-3x=\dfrac{1}{2}\)

=>-4x=1/2

=>x=-1/8

4: \(\Leftrightarrow x^2-x-x^2-x-\dfrac{1}{3}x=\dfrac{1}{4}x\)

=>-7/3x-1/4x=0

=>x=0

Answer 2

`1) 2x(3x-1/2)-x(6x-11)=30x`

`⇔ 6x^2-x-6x^2+11x=30x`

`⇔ 10x-30x=0`

`⇔ -20x=0`

`⇔ x=0`

Vậy `S={0}`

`2) x(7-4x)+2x(2x-1)=24`

`⇔ 7x-4x^2+4x^2-2x=24`

`⇔ 5x=24`

`⇔ x=24/5`

Vậy `S={24/5}`

`3) 1/2(x^2-2x)-x(1/2x+3)=1/2`

`⇔ 1/2x^2-x-1/2x^2-3x=1/2`

`⇔ -4x=1/2`

`⇔ x=(-1)/8`

Vậy `S={(-1)/8}`

`4) x(x-1)-x(x+1)-1/3x=1/4x`

`⇔ -2x-1/2x=1/4x`

`⇔ (-3)/4x=1/4x`

`⇔ (-3)/4x-1/4x=0`

`⇔ -x=0`

`⇔ x=0`

Vậy `S={0}`