SOLUTION: 1.prove that &#8730;3 is irrational 2.prove that if 0 < b < a and n is a positive integer,then a. b&#8319; < a&#8319; b. n&#8730;b < n&#8730;a where n&#8730; is the positive

Algebra ->  Real-numbers -> SOLUTION: 1.prove that &#8730;3 is irrational 2.prove that if 0 < b < a and n is a positive integer,then a. b&#8319; < a&#8319; b. n&#8730;b < n&#8730;a where n&#8730; is the positive      Log On


   



Question 252194: 1.prove that √3 is irrational
2.prove that if 0 < b < a and n is a positive integer,then
a. bⁿ < aⁿ
b. n√b < n√a where n√ is the positive nth term
c.1/bⁿ>1/aⁿ

Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
1.prove that √3 is irrational
 
Assume for contradiction that sqrt%283%29
equals a common fraction p%2Fq reduced to lowest terms.
That is, suppose there are integers p and q
with no common factors other than 1 such that
 
sqrt%283%29=p%2Fq
 
Square both sides:
 
3=p%5E2%2Fq%5E2
 
Multiply both sides by q%5E2
 
3q%5E2=p%5E2
 
q is either even or odd.  Suppose q is even.
Then q^2 is even. Then 3q^2 is even.  Therefore
p^2 is even, and therefore p is even.  That
contradicts the fact that p%2Fq was reduced
to lowest terms, since if both were even they
would have factor 2 in common.
 
So we have ruled out q being even,  So let's
suppose q is odd. Then q^2 is odd.  Therefore
3q^2 is odd. Therefore p^2 is odd. Therefore
p is odd.  So there must exist non-negative
integers m and n such that 
 
p = 2n+1 and q = 2m+1.  Substituting in
 
3q%5E2=p%5E2
 
3%282m%2B1%29%5E2=%282n%2B1%29%5E2
 
Squaring these out:
 
3%284m%5E2%2B4m%2B1%29+=+4n%5E2%2B4n%2B1
 
12m%5E2%2B12m%2B3+=+4n%5E2%2B4n%2B1
 
12m%5E2%2B12m%2B2+=+4n%5E2%2B4n
 
Divide through by 2:
 
6m%5E2%2B6m%2B1+=+4n%5E2%2B4n
 
The left side is odd but the 
right side is even.  That cannot
be, so q is not odd.
 
q cannot be even or odd, which cannot
be, so sqrt%283%29 is irrational.
 

2.prove that if 0 < b < a and n is a positive integer,then
a. b%5En%3Ca%5En

a%3Eb is given,

therefore a-b%3E0

by a factoring theorem



Since the second parentheses contains only positive terms,

a%5En-b%5En%3E0 which is the same as b%5En%3Ca%5En

b. root%28n%2Ca%29+%3C+root%28n%2Ca%29 where root%28n%2C%22%22%29 is the positive nth root

This follows by replacing a and b respectively with
root%28n%2Ca%29 and root%28n%2Cb%29 in part a. 

c. 1%2Fb%5En%3E1%2Fa%5En
 
b%5En%3Ca%5En by part a.  This is equivalent to:

a%5En-b%5En+%3E0

Divide through by the positive number a%5En%2Ab%5En

%28a%5En-b%5En%29%2F%28a%5En%2Ab%5En%29+%3E0 

a%5En%2F%28a%5En%2Ab%5En%29-b%5En%2F%28a%5En%2Ab%5En%29+%3E+0

1%2Fb%5En+-1%2Fa%5En%3E0

which is equivalent to 1%2Fb%5En%3E1%2Fa%5En 

Edwin