Question

Afla toate nr "x"care verifica inegalitatea:x×x×x<30

Answer 1

x³ < 30
=> 1³ = 1   < 30          => 1 x 1 x 1 = 1 
     2³ = 8    < 30         => 2 x 2 x 2 = 8
     3³ = 27  < 30         => 3 x 3 x 3 = 27
     4³ = 64 > 30
Deci x∈{1,2,3}

Answer 2

$x\times x\times x\ \textless \ 30 \Rightarrow x^3 \ \textless \ 30 \Rightarrow x \ \textless \ \sqrt[3]{30} \Rightarrow x \in (-\infty , \sqrt[3]{30})$