+0  
 
0
100
4
avatar

Find all integers n  for which

 

THANK YOU

 Jan 5, 2020
 #1
avatar+108624 
+2

There may be a better way but I started by expanding it all out and simplify

Taking it to one side and put equal to 0

 

After you do that and present your answer here I will help you more.

 Jan 5, 2020
 #2
avatar+33 
+1

n3= n3-1+n3-8+n3-27

n3=n3+n3+n3-1-8-27

n3=3n3-9-27

n3=3n3-18

-n3+n3=-18/3

6 (ans)

 Jan 5, 2020
 #3
avatar+108624 
+1

Hi Sadaatkhan,

 

It is good to see you haviing a go ... but...

 

Your woking is not correct

(n-1)^3 is not n^3-1

Melody  Jan 5, 2020
edited by Melody  Jan 5, 2020
 #4
avatar+1068 
0

Expanding a little bit on Melody's answer...

You expand and get \(n^3 = (n^3-3n^2-3n+1)+(n^3-6n^2+12n+8)+(n^3-9n^2+27n-27)\).

Solve from here.

 Jan 5, 2020

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