Đáp án:
`a)S={7/4}`
`b)S={-5/2}`
`c)S={9/8}`
`d)S={1/4}`
Giải thích các bước giải:
`a)(x-2)²-(x-3)(x+3)=6`
`⇔x²-4x+4-(x²-9)=6`
`⇔x²-4x+4-x²+9=6`
`⇔(x²-x²)-4x+(4+9)=6`
`⇔-4x+13=6`
`⇔-4x=6-13`
`⇔-4x=-7`
`⇔x=7/4`
Vậy `S={7/4}`
`b)(x+3)²+(4+x)(4-x)=10`
`⇔x²+6x+9+16-x²=10`
`⇔(x²-x²)+6x+(9+16)=10`
`⇔6x+25=10`
`⇔6x=10-25`
`⇔6x=-15`
`⇔x=-15/6`
`⇔x=-5/2`
Vậy `S={-5/2}`
`c)4(x-3)²-(2x-1)(2x+1)=10`
`⇔4(x²-6x+9)-(4x²-1)=10`
`⇔4x²-24x+36-4x²+1=10`
`⇔(4x²-4x²)-24x+(36+1)=10`
`⇔-24x+37=10`
`⇔-24x=10-37`
`⇔-24x=-27`
`⇔x=27/24`
`⇔x=9/8`
Vậy `S={9/8}`
`d)-4(x-1)²+(2x-1)(2x+1)=-3`
`⇔-4(x²-2x+1)+4x²-1=-3`
`⇔-4x²+8x-4+4x²-1=-3`
`⇔(-4x²+4x²)+8x-(4+1)=-3`
`⇔8x-5=-3`
`⇔8x=-3+5`
`⇔8x=2`
`⇔x=2/8`
`⇔x=1/4`
Vậy `S={1/4}`
