Question

If $\alpha$ and $\beta$ are roots of the quadratic equation ${3x}^2+3x+2=0$ then ${\alpha }^3+{\beta }^3$=.......

• A. $-\frac{1}{3}$
• B. $-1$
• C. 1
• D. None of the above

Answer 1

Answer: (C)

1

$a=3,b=3,c=2$
$\Rightarrow \alpha +\beta =-1,\alpha \beta =\frac{2}{3}$
${\alpha }^3+{\beta }^{}={(-1)}^3-3\times \frac{2}{3}\times (-1)$
$=-1+2=1$