Sunday, August 19, 2018

mathematical puzzle


Fun with Mathematics
If p and q are positive and real numbers such that p2  +  q2 = 1 . What are the maximum and minumum values of (p+q)  ?
Solution:
P2  = 1 – q2  = (1 + q) (1 –q). Let  1 + q = kp  and 1-q = p/k. By solving these two equations, we have
P = 2k/(k2+ 1)  and  q = (k2 – 1)/(k2 + 1). If p+q is maximum  p and q must be equal or k2 -2k -1 = 0 . It gives k = (1 + 2) or p = q =(1 +2)/(2+2) It gives p+q = 2.
If p+q is minimum the difference between them must be maximum provided p or q cannot be greater than 1. 1+ q = p2 and 1- q = 1. It is possible only when p = 1 and q = 0..So the minimum value of p+q = 1   

Saturday, August 4, 2018

Discipline in Digital world


Discipline in digital world
Abstract: All numbers are having its own characteristics when mixed together in a relation, they show strict discipline which is curious to know. The disciplinary behavior of a group of numbers is quite amazing when exposed. Few inherent disciplines in the digital world are described in this article.
Key words: Number theory, Numeral relations- Triangular numbers
Introduction:
In numeral relations, two or more numbers are connected together with some mathematical operators When the numbers are varied under the same condition, the disciplinary behaviors of the numbers strike our mind. The inherent disciplines of a group of numbers in the digital world are exemplified with few simple numeral relations.
1.Sum of three squares of two successive numbers and its product
Sum of two squares of any two successive numbers is added with the square of its product always gives a square, the root number of which is one excess over the product number. This in turn is a factor for the sum of fourth powers of the same set of numbers.
12  + 22 + 22  = 32  ;  14  + 24  + 24  = 33 = 3 x 11
22 + 32  + 62  = 72 ; 24 + 34  + 64  = 1393 = 7 x 199
32  + 42  + 122 = 132 ;  34  + 44  + 124 = 21073 = 13 x 1621
42 + 52 + 202   = 212 ; 44 + 54 + 204   = 160881 = 21 x 7661
For any number n, it can be expressed as  n2 + (n+1)2  +[n(n+1]2  =[ n(n+1) +1]2   and it is found that [n(n+1) + 1] is always a factor for  n4 + (n+1)4  +[n(n+1]4
2. Sum of three squares of any two numbers and its sum
Sum of squares of any two numbers when added with the square of its sum has a peculiar property . Half of the sum when added with the product of the two numbers taken gives the square of its sum 
   12  +  122  + 132  =  2 x 157 ; 157 + 1 x 12 = 132
    22  + 112  + 132 = 2 x 147 ; 147 + 2 x 11 = 132
   32  + 102  + 132  = 2 x 139 ; 139 + 3 x 10 = 132
  42 +  92  + 132  = 2 x 133 ; 133 + 4 x 9 = 132
For any two numbers m and n, we have
m2  + n2 + (m+n)2  =  2( m2 + n2  + mn)  ; m2  + n2 + mn + (m x n) = (m+n)2
3. Sum of four different powers of any four successive numbers
  It is found that the sum of four different powers of any four successive numbers where both the numbers and the exponents are in ascending order has some curious properties
1 + 22 + 33 + 44  = 288 = 2 x 144 = 3 x 42 x 6
2 + 32 + 43 + 54 = 700 = 7 x 100 = 4 x 52  x 7
3 + 42 + 53 + 64  = 1440 = 10 x 144 = 5 x 62 x 8
4  + 52  + 63 + 74 = 2646 = 6 x 441 = 6 x 72 x 9
In general, n  + (n+1)2 + (n+2)3 + (n+3)4  = (n+2) (n+3)2 (n+5)
With any three successive numbers, we have
1 + 22 + 33  = 32 = 2 x 42
2 + 32 + 43 = 75 = 3 x 52
3 + 42 + 53  = 144 = 4 x 62
4  + 52  + 63 = 245 = 5 x 72
In general, n + (n+1)2  + (n+2)3 = (n+1) (n+3)2
4 The sum of any three successive numbers when added with its mean gives the cube of that mean
 1 x 2 x 3 + 2 = 23
2 x 3 x 4 + 3 =  33
3 x 4 x 5 + 4 = 43
In terms of n
n x (n+1) x (n+2) + (n+1) = (n+1)3
The square and cube of successive numbers are related with successive triangular numbers Tn
 which are nothing but the sum of natural numbers from 1 to n, 1,3,6,10,15,21,28,36,45,55,66,78………. [n(n+1)]/2
12  = 1
22  =  2 + 2(1)
32 = 3 + 2(3)
42 = 4  + 2(6)
n2  = n + 2(Tn-1)
The cubes have different correlation with the triangle numbers
13 = 1
23  = 2 + 6(1)
33 =  3 + 6 (1+3)
43  = 4 + 6(1+3+6) 
n3  = n + 6 x ( Tn-1)2
The fourth power of a number
14  = 1
24  =  22  + 12 (1)                                                                        
34 =  32  + 12 (1+4)
44   = 42  + 12( 1+4+ 9)
In general, n4  = n2 + 12  n-1 x2           
                                              1

Wednesday, August 1, 2018

More about Triangular numbers
Introduction:
The triangular number is a kind of figurate number that can be represented in the form of a triangular grid of dots or unit number 1, where the rows denotes its order n and the total counts up to that row gives the n th  triangular number. Simply said , the sum of the natural numbers up to n  is the n th triangular number and is denoted by Tn. which can be mathematically expressed as  Tn  =  n (n+1)/2. 
Properties of Triangular numbers;
The triangular numbers has many interesting properties. Some of them are 
1. All perfect numbers  are invariably triangular numbers. First few triangular numbers which are also perfect are 6 (T3) . 28 (T7), 496 (T31), 8128 (T127) 2. The natural series of triangular numbers are continuous alternate blocks of pair of odd and even numbers The sum of two numbers in any block gives even square while one from a block and the neighbouring  number in the adjacent block gives odd square. In all cases the sum of any two successive triangular numbers is a square of higher order among them Tn-1 + Tn  = n2  and Tn  + Tn+1  = (n+1)2. Subtracting one from the other we get an identity (n+1)2 – n2 =   Tn+1   -  Tn-1  = (2n +1) , which predicts that an odd number can be represented not only as a difference of  squares of two numbers with a difference of odd number but also as a difference of two triangular numbers whose orders are one above and below n. The difference between the fourth powers of any two successive numbers gives yet another identity  (n+1)4  - n4 = (2n+1) [ Tn+1 + Tn-1  + 2Tn] 3. A square can be expressed in terms of triangular numbers by three ways. n2  = Tn-1 + Tn = T(n2)  - T (n2 – 1)  = n + 2Tn-1’  It gives an identity T(n2) – Tn  = T(n2 -1) – Tn-1
4. With any successive three triangular numbers Tn-1, Tn ,Tn+1  , one can get an identity Tn-1 + T (n2) + Tn+1  = (n+1)2. A kind of discipline is found in such identity with 5,7,9------ successive triangular numbers. Tn-2 + Tn-1 + T (n2) + Tn+1 + Tn+2 = (n+2)2  + 1 Tn-3 +      Tn-2 + Tn-1 + T (n2) + Tn+1 + Tn+2 + Tn+3   = (n+3)2  + (1+4) Tn-4 + Tn-3 + Tn-2 + Tn-1 + T (n2) + Tn+1 + Tn+2 +Tn+3 + Tn+4 = (n+4)2 + (1+4+9) In general with m number of triangular numbers above and below the n th  triangular number, we get

 Tn-m  + Tn-m+1 + Tn-m+2 + ………………….  Tn2 + Tn+1 + Tn+2 + …………… Tn+m  = (n+m)2 +   (m-1) ∑ x2                                                                                                                                                     1                                       
          5 .  Any three triangular numbers with a common difference D in its order shows yet                                                                                                                                                  another numeral discipline
                   D = 1,  Tn-1 + (Tn)2  + Tn+1   = (Tn + 1)2       D = 2 , Tn-2  +  (Tn)2  + Tn+2  = (Tn  + 1)2 + (22  - 1)                                                                                                                                                                                                                                                                                                                                                 D = 3 , Tn-3  +  (Tn)2  + Tn+3  = (Tn + 1)2  + (32 – 1)                                                                                                                                                       In general, when any common difference D = m, Tn-m  +  (Tn)2  + Tn+m  = (Tn  + 1)2  + (m2 – 1) 6 Not only square but also any Power of any number cab be expressed in terms of triangular numbers. n3 = (Tn-1 + Tn) n  = n + 6 [ n-1 ∑ Tx ]                    1                         n4 = n2  + 4 Tn Tn-1 n5  = n3  + 6 n2   n-1 ∑ Tx    = n3  + 4n Tn-1  Tn
                                           
1 n6 = n2 + 12 [ n2 + 3 n-1 ∑ Tx ]  [n-1 ∑ Tx]                                                                                                                                                                                                                                                                                                                1                            1  7     The Pythagorean triples (a,b,c) satisfying the relation  a2  + b2   = c2  have some correlation with its corresponding triangular numbers. Substituting the values for a.b.c  in  terms of triangular numbers using the property (3) we have . T (c2) – T(b2) – T(a2)   =  T(c2 -1) – T(b2 – 1)  - T (a2 – 1)  = (ab)2                      Tc – Tb  - Ta   = Tc-1 – Tb-1 – Ta-1 a + b – c = 2 [ Tc-1 – Tb-1 – Ta-1]  It gives an additional condition required for Fermat’s assertion that  the relation an  + bn  = cn  where a,b,c are all positive integers  and the exponent n > 2 has no whole integral solutions.

T(cn)  -  T(bn)  - T(an)  = T(cn- 1)  - T(bn-1) – T(an- 1)

               8. Innumerable identities can be obtained for every Beal’s expression.  Considering the simplest                                                                                                                                                                                                                                                 irreducible form of a Beal’s relation  1+ 8 = 9 and using the property (3) we have                 T1 + T64 – 2T7 – T63  = T81 – 2T8  - T80             9. There are infinitely many square triangular numbers,  the first few positive numbers are               1(T1),36(T8) ,1225 (T49),41616 (T288) ,1413721(T1681) ,48024900 (T9800) ,1631432881( T57121),55420693056 (T332928)………… The order and the corresponding square triangular numbers can be determined very
simply from the knowledge of the two product factors of any known square triangular number.  Let a2 and b2  are the two product factors of a square triangular number Tx . If a and b are both odd and b>a, then the order of the square triangular number is b2, if a is even and b is odd, then its order will be          b2 – 1. One of the two product factors of the next higher order square triangular number would invariably be  (a+b)2 and the other product factor depends upon the odd-evenness of the given factors a,b. If both are odd the other product factors is (a+b+  smaller odd number in a,b)2, if one is odd and other is even, the other product factors is (a+b + even number in a,b)2.    Conclusion:  The identities with triangular numbers can be used as a tool  to study  relations in number theory