Question

please give answer complete . I have to write this in notebook

Answer 1

let the no be x
it is doubled=2x
cube of x = x*x*x
             = x to the power of 3 
cube of 2x = 2x*2x *2x
                 = 8 x to the power of 3       
thus cube of x and cube of 2x has a difference of 8 times
hence it is proved

Answer 2

Let the number be x.

its cube = x cube

the double of the number = 2x.

cube of its double = (2x)cube = 2cube*x cube = 8x cube

= 8 times  the cube of the original number.

hope this helps you.