Question

A cube has a lateral area of 9 square centimeters. What is the length of each edge of the cube?

Answer 1

the answe on edg is 1.5

Answer 2

Check the picture below, that'd be a cube, all equal sides so 6 squares really, its lateral or sides section are just the squares at front, back, left, right.

if say, one side is hmm "s" units long, the area of just one square is s*s or s², and the area of those four lateral squares will just be 4(s²), or 4s² then.

now, we know the lateral area is 9 cm², namely 9 = 4s², thus

$\bf 9=4s^2\implies \cfrac{9}{4}=s^2\implies \sqrt{\cfrac{9}{4}}=s\implies \cfrac{\sqrt{9}}{\sqrt{4}}=s\implies \cfrac{3}{2}=s$

and surely you know how much that is.