Đáp án:
`a)x=4/3`
`b)x=1/2`
`c)x=0` hoặc `x=-2`
Giải thích các bước giải:
`a)(3x+4)²-(3x-1)(3x+1)=49`
`⇔9x²+24x+16-(9x²-1)=49`
`⇔9x²+24x+16-9x²+1=49`
`⇔24x+17=49`
`⇔24x=49-17`
`⇔24x=32`
`⇔x=32/24`
`⇔x=4/3`
Vậy `x=4/3`
`b)(3x-1)²-(3x-2)²=0`
`⇔(3x-1+3x-2)(3x-1-3x+2)=0`
`⇔(6x-3).1=0`
`⇔6x-3=0`
`⇔6x=3`
`⇔x=3/6`
`⇔x=1/2`
Vậy `x=1/2`
`c)(2x+1)²-(x-1)²=0`
`⇔(2x+1+x-1)(2x+1-x+1)=0`
`⇔3x(x+2)=0`
`⇔`\(\left[ \begin{array}{l}3x=0\\x+2=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=0\\x=-2\end{array} \right.\)
Vậy `x=0` hoặc `x=-2`
