Math Is Fun Forum

That was intentional.

Abbr. Sr.
Used as a courtesy title before the surname, full name, or professional title of a man in a Spanish-speaking area.
Used as a form of polite address for a man in a Spanish-speaking area.
(Spanish)

Problem # k + 41

Prove that the number 512³ + 675³ + 720³ is not prime.

Well done, Mathsy!

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The statistics on sanity are that one out of every four persons is suffering from some sort of mental illness. Think of your three best friends, if they are okay, then...

I am Ganesh, from Chennai, India, one of the Moderators.

Hi m_f,
Welcome to the forum.
Nice pic.

sin(x)  = sin(0) + xcos(0) −x²sin(0)/2! − x³ cos(0)/3!
+ x^4 sin(0)/4! - x^5 cos(0)/5! + ...............
= x - x³/3! + x^5/5! - x^7/7!................

Let white=0, black=1;
white + black = 0 + 1 = 1 = black
white + white = 0 + 0 = 0 = white, Proved!

For A), B) please give some time. Yes, Proofs aren't too easy. They are time consuming.

This page would be of help.
A linear equation has to necessarily be of degree 1. (degree of a polynomia or an equation is the highest power of any varibale)

Problem # k + 37

A string of 1996 digits begins with the number 6. Any number formed by two consecutive digits is divisible by 17 or 23. The number contains two consecutive digits which are multiples of 17 and multiples of 23. What is the last digit?

Problem # k + 36

Is it true that n^3+5n-1 is prime for any natural n?

Thats correct, Mathsy!