What you mean is that for any integer x, x^5 - x is divisible by 30, the subject being, not high-school algebra but number theory.
Every number is a multiple of 6 plus one of {0,1,2,3,4,5}.
[6x + {0,1,2,3,4,5}]^5 has what remainders when you divide by 6? For example 2^5 = 32 = 6*5 + 2. In other words
(6x + 2)^5 = 6z + 2, for some z. You will find that if you start with any number {0,1,2,3,4,5} you will have the same as remainders. So if you subtract them, X^5 - X will have remainders of zero. This means that X^5 - X is always divisible by six.
You can do the same thing with (5x + {0,1,2,3,4})^5 and you will find out the same thing; that all numbers of the form
x^5 - x are divisible by 5. Therefore it is also divisible by 30.
See Fermat's "little theorem" which applies here to the "divisible by five" part of the above argument.
2007-07-25 06:34:15
·
answer #1
·
answered by Anonymous
·
0⤊
0⤋
x^5 - x = x(x^4 - 1). If x = 30 then the original statement is divisible by 30.
2007-07-25 12:31:21
·
answer #2
·
answered by John V 6
·
0⤊
0⤋
Anything can be divided by 30.
Are you asking if you get a whole number or a rational number or what?
2007-07-25 12:32:30
·
answer #4
·
answered by TychaBrahe 7
·
0⤊
1⤋
huh?
x^5-x=
x(x^4-1)
now if x was 2, then x(x^4-1) would equal 30, i'm not sure what you're looking for
2007-07-25 12:30:05
·
answer #5
·
answered by jnice160 2
·
0⤊
1⤋