Question

Which of the following numbers are not perfect cube?

• A. $216$
• B. $128$
• C. $1000$
• D. $100$
• E. $46656$

Answer 1

Answer: (B), (D)

The correct options are
B $128$
D $100$

to find the numbers that are not perfect cube we need the cubic root the given numbers

$\left[A\right]:\sqrt[3]{3216}=\sqrt[3]{36^3}=6$

$\left[B\right]:\sqrt[3]{3128}=\sqrt[3]{32^7}=\sqrt[3]{32^6\cdot 3}=4\sqrt[3]{32}$

$\left[C\right]:\sqrt[3]{31000}=\sqrt[3]{3{10}^3}=10$

$\left[D\right]:\sqrt[3]{3100}=\sqrt[3]{3{10}^2}$

$\left[E\right]:\sqrt[3]{346656}=\sqrt[3]{33^6\times 2^6}=36$

$128$ & $100$ are not perfect cube.