Solve by making a u-substitution
-$x^{2 / 3}-2 x^{1 / 3}-15=0$
A) $\{-27,125\}$
B) $\{27,125\}$.
C) $\{-27,-125\}$
D) $\{27,-125\}$.

Question

Quizplus · Accepted Answer

By letting $u = x^{1/3}$, the equation becomes $u^2 - 2u - 15 = 0$, which factors to $(u-5)(u+3) = 0$. Solving for $u$ gives $u = 5$ and $u = -3$. Reverting back to $x$, we have $x^{1/3} = 5$ and $x^{1/3} = -3$, leading to $x = 5^3 = 125$ and $x = (-3)^3 = -27$, respectively.

Solve by Making a U-Substitution - x2/3−2x1/3−15=0x^{2 / 3}-2 x^{1 / 3}-15=0x2/3−2x1/3−15=0

Solve by Making a U-Substitution
- $x^{2 / 3}-2 x^{1 / 3}-15=0$