The product of the roots of the equation $\sqrt[3]{8+x}+\sqrt[3]{8-x}=1$, is ______.
Answer & explanation
We have,
$\sqrt[3]{8+x}+\sqrt[3]{8-x}=1$
$(\sqrt[3]{8+x}+\sqrt[3]{8-x})^3=(1)^3$ [On cubing both sides]
$⇒8+x+8-x+3(64-x^2)^{1/3}(\frac{\sqrt[3]{8+x}+\sqrt[3]{8-x}}{1})=1$
$⇒16+3(64-x^2)^{1/3}=1$
$⇒15=-3(64-x^2)^{1/3}$
$⇒(64-x^2)^{1/3}=-5$
$⇒64-x^2=-125 ⇒x^2=189 ⇒ x=± 3\sqrt{21}$
Product of roots = $3\sqrt{21} × - 3\sqrt{21}=-189$