$\text {→Bài}$ `1:`
`a,`
`(4x+1)(x-3) = (x-7)(4x-1)+15`
`⇔4x^2-12x+x-3 = 4x^2-x-28x+7+15`
`⇔4x^2-11x-3 = 4x^2-29x+22`
`⇔4x^2-4x^2-11x+29x = 3+22`
`⇔18x = 25`
`⇔x = (25)/(18)`
$\text {Vậy}$ `x=(25)/(18)`
`b,`
`(x+1)(x^2-x+1)-x(x^2-3) = 4`
`⇔x^3+1-x^3+3x = 4`
`⇔3x = 3`
`⇔x=1`
$\text {Vậy }$ `x=1`
`c,`
`(x-3)(x^2+3x+9)+x(5-x^2) = 6x`
`⇔x^3-27+5x-x^3 = 6x`
`⇔5x-6x = 27`
`⇔-x = 27`
`⇔x = -27`
$\text {Vậy}$ `x=-27`
`d,`
`(3x-5)(x+1)-(3x-1)(x+1) = x-4`
`⇔(x+1)(3x-5-3x+1) = x-4`
`⇔-4(x+1) = x-4`
`⇔-4x-4 = x-4`
`⇔-4x-x = 4-4`
`⇔-5x = 0`
`⇔x = 0`
$\text {Vậy}$ `x=0`
$\text {→Bài}$ `2:`
`a,`
`5x^2+(2x+1)(2-x)-x(3x+3)+7`
`= 5x^2+4x-2x^2+2-x-3x^2-3x+7`
`= 9`
`b,`
`(3x-1)(2x+3)+(x-5)(1-6x)-38x`
`= 6x^2+9x-2x-3+x-6x^2-5+30x-38x`
`= -8`
`c,`
`(5x-2)(x+1)+(3-x)(5x+1)-17(x-2)`
`= 5x^2+5x-2x-2+15x+3-5x^2-x-17x+34`
`= 35`
`d,`
`(4x-5)(x+2)-(x-3)(x+5)-3x^2-x`
`= 4x^2+8x-5x-10-x^2-5x+3x+15-3x^2-x`
`= 5`
$\text {@lamtung2007}$
