`a)`
`3(1-4x)(x-1)+4(3x+2)(x+3)=38`
`⇔(3-12x)(x-1)+(12x+8)(x+3)=38`
`⇔3x-3-12x^2+12x+12x^2+36x+8x+24=38`
`⇔(3x+12x+36x+8x)+(-12x^2+12x^2)=38+3-24`
`⇔59x=17`
`⇔x=17/59`
Vậy `x=17/59`
`b)`
`5(2x+3)(x+2)-2(5x-4)(x-1)=75`
`⇔(10x+15)(x+2)-(10x-8)(x-1)=75`
`⇔10x^2+20x+15x+30-(10x^2-10x-8x+8)=75`
`⇔10x^2+35x+30-10x^2+10x+8x-8=75`
`⇔(10x^2-10x^2)+(35x+10x+8x)=75-30+8`
`⇔53x=53`
`⇔x=1`
Vậy `x=1`
`c)`
`2x^2+3(x-1)(x+1)=5x(x+1)`
`⇔2x^2+3(x^2-1)=5x^2+5x`
`⇔2x^2+3x^2-3=5x^2+5x`
`⇔(2x^2+3x^2-5x^2)-5x=3`
`⇔-5x=3`
`⇔x=-3/5`
Vậy `x=-3/5`
`d)`
`(8-5x)(x+2)+4(x-2)(x+1)+2(x-2)(x+2)=0`
`⇔8x+16-5x^2-10x+(4x-8)(x+1)+2(x^2-4)=0`
`⇔8x+16-5x^2-10x+4x^2+4x-8x-8+2x^2-8=0`
`⇔(8x-10x+4x-8x)+(-5x^2+4x^2+2x^2)+(16-8-8)=0`
`⇔-6x+x^2=0`
`⇔x(-6+x)=0`
`1)x=0`
`2)-6+x=0⇔x=6`
Vậy `x∈{0;6}`
