Question

Arãtati ca numarul b=2•(1+2+3+•••+124)+125 este cub perfect

Answer 1

b = 2(1+2+...+124) + 125
= 2 * 124 * 125 : 2 + 125
= 124*125 + 125
= 125(124+1)
= 125*125
$=125^2$
$=(5^3)^2$
$=(5^2)^3$

Answer 2

2*124*125/2 +125= 124*125+125= 125(124+1)= 125*125= 5³ * 5³=5^6=
5^(2*3)=(5²)³ =25³, cub perfect