Question

aratati ca 4 la puterea 21este patrat perfect si cub perfect​

Answer 1

Pătrat perfect (trebuie să fie la puterea a doua): 4²¹=(2²)²¹=(2²¹)²;

Cub perfect (puterea a treia): 4²¹=(4⁷)³;

Answer 2

$4^{21} = 4^{3\cdot 7} = (4^7)^3\to \text{cub perfect.} \\\\4^{21} = (2^2)^{21} = 2^{2\cdot 21}= (2^{21})^2\to \text{ patrat perfect.}\\ \\ \Rightarrow 4^{21} \text{ este patrat, respectiv cub perfect.}$