If $\frac{a}{b}+\frac{b}{a}=-1$ and a - b = 2, then the value of $a^3 - b^3$ is:
Answer & explanation
Correct answer: option 1
$\frac{a}{b}+\frac{b}{a}=-1$
\(\frac{a^2 + b^2}{ab}\) = -1
a2 + b2 = -ab
a - b = 2
a3 - b3 = ( a - b ) ( a2 + b2 + ab )
a3 - b3 = ( 2 ) ( -ab + ab )
a3 - b3 = 0