a) (2x +3)(x - 4) + (x - 5)(x - 2) = (3x - 5)(x - 4)

⇔ 2x² - 8x + 3x - 12 + x² - 2x - 5x + 10 = 3x² - 12x - 5x + 20

⇔ 2x² + x² - 3x² - 8x + 3x - 2x - 5x + 12x + 5x = 20 + 12 - 10

⇔ 5x = 22

⇔ x = $\frac{22}{5}$ 

b)  (8x - 3)(3x +2 ) - ( 4x + 7 )(x + 4) = ( 4x + 1 ) ( 5x - 1 )

⇔ 24x² + 16x - 9x - 6 - 4x² - 16x - 7x - 28 = 20x² - 4x + 5x - 1

⇔ 24x² - 4x² - 20x² + 16 x - 9x - 16x - 7x + 4x - 5x = 6 + 28 - 1

⇔ -17x = 33

⇔ x = $\frac{-33}{17}$ 

c)  2x^2 + 3(x - 1)(x + 1 ) = 5x(x + 1 )

⇔ 2x² + 3( x² - 1 ) = 5x² + 5x

⇔ 2x² + 3x² - 3 = 5x² + 5x

⇔ 2x² + 3x² - 5x² - 5x = 3

⇔ -5x = 3

⇔ x = $\frac{-3}{5}$ 

d) ( 8 - 5x) ( x + 2 ) + 4(x - 2)(x + 1 ) + ( x - 2 ) ( x + 2 ) = 0

⇔ 8x + 16 - 5x² - 10x + 4 ( x² + x - 2x - 2 ) + x² - 4 = 0

⇔ 8x + 16 - 5x² - 10x + 4x² + 4x - 8x - 8 + x² - 4 = 0

⇔ -5x² + 4x² + x² + 8x - 10x + 4x - 8x = 4 + 8 - 16

⇔ -6x = -4

⇔ x = $\frac{-4}{-6}$ 

⇔ x = $\frac{2}{3}$ 

chúc bạn học tốt

#anhduongtruong

Đáp án:

Giải thích các bước giải:

`a) (2x +3)(x - 4) + (x - 5)(x - 2) = (3x - 5)(x - 4)`

`⇔ 2x² - 8x + 3x - 12 + x² - 2x - 5x + 10 = 3x² - 12x - 5x + 20`

`⇔ 2x² + x² - 3x² - 8x + 3x - 2x - 5x + 12x + 5x = 20 + 12 - 10`

`⇔ 5x = 22`

`⇔ x = 225225`

`b)  (8x - 3)(3x +2 ) - ( 4x + 7 )(x + 4) = ( 4x + 1 ) ( 5x - 1 )`

`⇔ 24x² + 16x - 9x - 6 - 4x² - 16x - 7x - 28 = 20x² - 4x + 5x - 1`

`⇔ 24x² - 4x² - 20x² + 16 x - 9x - 16x - 7x + 4x - 5x = 6 + 28 - 1`

`⇔ -17x = 33`

`⇔ x = −3317−3317`

`c)  2x^2 + 3(x - 1)(x + 1 ) = 5x(x + 1 )`

`⇔ 2x² + 3( x² - 1 ) = 5x² + 5x`

`⇔ 2x² + 3x² - 3 = 5x² + 5x`

`⇔ 2x² + 3x² - 5x² - 5x = 3`

`⇔ -5x = 3`

`⇔ x = −35−35`

`d) ( 8 - 5x) ( x + 2 ) +4 (x - 2)(x + 1 ) + ( x - 2 ) ( x + 2 ) = 0`

`⇔ 8x + 16 - 5x² - 10x + 4 ( x² + x - 2x - 2 ) + x² - 4 = 0`

`⇔ 8x + 16 - 5x² - 10x + 4x² + 4x - 8x - 8 + x² - 4 = 0`

`⇔ -5x² + 4x² + x² + 8x - 10x + 4x - 8x = 4 + 8 - 16`

`⇔ -6x = -4`

`⇔ x = −4−6−4−6`

`⇔ x = 2323`

Xin hay nhất !