Đáp án:
`a)x=-9/10`
`b)x=-4/5`
`c)x=-1`
Giải thích các bước giải:
`a)(x+1)(2-x)-(3x+5)(x+2)=-4x²+1`
`⇔2x-x²+2-x-(3x²+6x+5x+10)=-4x²+1`
`⇔2x-x²+2-x-3x²-6x-5x-10=-4x²+1`
`⇔(-x²-3x²)+(2x-x-6x-5x)+(2-10)=-4x²+1`
`⇔-4x²-10x-8=-4x²+1`
`⇔-4x²-10x+4x²=1+8`
`⇔-10x=9`
`⇔x=-9/10`
Vậy `x=-9/10`
`b)(2x+2)(x-1)-(x+2)(2x+1)=0`
`⇔2x²-2x+2x-2-(2x²+x+4x+2)=0`
`⇔2x²-2x+2x-2-2x²-x-4x-2=0`
`⇔(2x²-2x²)+(-2x+2x-x-4x)-(2+2)=0`
`⇔-5x-4=0`
`⇔-5x=4`
`⇔x=-4/5`
Vậy `x=-4/5`
`c)(3x+1)(2x-3)-6x(x+2)=16`
`⇔6x²-9x+2x-3-6x²-12x=16`
`⇔(6x²-6x²)-(9x-2x+12x)-3=16`
`⇔-19x-3=16`
`⇔-19x=16+3`
`⇔-19x=19`
`⇔x=19:(-19)`
`⇔x=-1`
Vậy `x=-1`
