Question

The roots of the quadratic equation $3x^2+2x-1=0$ are .

• A. 1, $\frac{1}{3}$
• B. -1, $\frac{1}{3}$
• C. 2, 3
• D. -2, $\frac{1}{3}$

Answer 1

The correct option is B -1, $\frac{1}{3}$

$3x^2+2x-1=0$
$\Rightarrow 3x^2+3x-x-1=0$
$\Rightarrow 3x(x+1)-1(x+1)=0$
$\Rightarrow (3x-1)(x+1)=0$
$\Rightarrow$ $(3x-1)=0or(x+1)=0$
$\Rightarrow x=\frac{1}{3}orx=-1$
$\therefore$ The roots of the given equation are $-1$, $\frac{1}{3}$ .