Đáp án:
Giải thích các bước giải:
`3x^2+3x-1=0`
`<=>x^2+x-1/3=0`
`<=>x^2+x+1/4-7/12=0`
`<=>(x+1/2)^2-7/12=0`
`<=>(x+1/2)^2=7/12`
`<=>x+1/2=+-sqrt(7/12)`
`<=>`\(\left[ \begin{array}{l}x+\dfrac{1}{2}=\sqrt{\dfrac{7}{12}}\\x+\dfrac{1}{2}=-\sqrt{\dfrac{7}{12}}\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=\sqrt{\dfrac{7}{12}}-\dfrac{1}{2}\\x=-\sqrt{\dfrac{7}{12}}-\dfrac{1}{2}\end{array} \right.\)
