Prove that any positive odd integer is of the form 4n+1 4n+3
Answers
Answer :
Step-by-step explanation:
Let 'a' be any positive odd integer and b = 4.
Using Euclid Division Lemma
a = bq + r [ 0 ≤ r < b ]
⇒ a = 4q + r [ 0 ≤ r < 4 ]
Now, possible value of r :
r = 0, r = 1, r = 2, r = 3,
CASE I :
If we take, r = 0
⇒ a = 4q + 0
⇒ a = 4q
⇒ a = 2 ( 2q )
⇒ a = 2n. [ n = 2q as an integer ]
So, it is rejected because it is an even number.
CASE II :
If we take, r = 1
⇒ a = 4q + 1
⇒ a = 4n + 1 [ n = q as an integer ]
As it cannot be expressed in 2n form, it is an odd number which is in the form 4n + 1.
CASE III :
If we take, r = 2
⇒ a = 4q + 2
⇒ a = 4n + 2
⇒ a = 2 (2n + 1 ) [ n = q as an integer ]
As it can be expressed in (2n + 1)form, it is an even number.
CASE IV :
If we take, r = 3
⇒ a = 4q + 3
⇒ a = 4n + 3 [ n = q as an integer ]
As it cannot be expressed in 2n form, it is an odd number which is in the form 4n + 3.
Hence, it is proved that any positive odd integer is of the form 4n+1 and 4n+3.
Step-by-step explanation:
Let a be any positive odd integer and b=4
So by applying division lemma to a,b
a=4q+r where 0≤r<4
When r=0
a=4q+0=4q=2(2q)
When r=1
a=4q+1
When r=2
a=4q+2=2(2q+1)
When r=3
a=4q+3
Since 4q,4q+2 are multiple of 2 so they are even numbers
So every positive odd integer is of the form (4q+1) or (4q+3) where q is some integer
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