PROPERTIES OF COMPLEX NUMBER
There are some property of complex number under +, −, ×, ÷ we prove these properties any value of complex number we take variable a₁, b₁,c₁,d₁,e₁, f₁
ADDITION ( + ) complex number multiplication
( i ): closure property (+)
when (a₁+b₁) ,(c₁ + d₁ ) ∈ ℂ
= (a₁+ b₁)+ (c₁ + d₁ )
=(a₁ +c₁) + (b₁+d₁) ∈ ℂ (say closed + in complex number )
( ii ): associative property ( + )
once (a₁+b₁) , (c₁ ,d₁ ) , (e₁ , f₁ ) ∈ ℂ
[ ( (a₁+b₁) + (c₁ +d₁ ) ] + (e₁ + f₁ )
= ( (a₁+ c₁) +e₁ ( b₁ + d₁ ) + f₁
= [ a₁ + ( c₁+ e₁ ) , b₁ + ( d₁ + f₁) ]
as a result of addition is associative in R what is complex plane
= (a₁ , b₁) +( c₁+ e₁ ) + ( d₁ + f₁)
= (a₁ , b₁) + [( c₁+ d₁ ) + ( e₁ + f₁) ] thence verify
(iii) additive identity ( + )
∀ ( a₁ ,b₁) ∈ ℂ
we have ( 0 , 0 ) ∈ ℂ
such that ( a₁ , b₁) + ( 0 , 0 )
= ( a₁+0 , b₁+ 0)
= ( a₁ , b₁)
this implies that ( 0 , 0 ) is additive identity in ℂ
∀ ( a₁ ,b₁) ∈ ℂ inverse is ( -a₁ , -b₁) ∈ ℂ
( a₁ - a₁ ) + ( b₁ -b₁ )
= ( 0 , 0 )
this implies that ( a₁ ,b₁) and ( -a₁ , -b₁) are additive inverse of each other
(v) commutative property(+):
when (a₁+b₁) ,(c₁ + d₁ ) ∈ ℂ
(a₁+b₁) +(c₁ + d₁ ) = (c₁ + d₁ ) + (a₁+b₁)
(a₁ +c₁) + (b₁+d₁) = (c₁ + a₁ ) +( d₁ + b₁)
as a result of addition is commutative in R
(a₁ +c₁) + (b₁+d₁) = (c₁ + a₁ ) +( d₁ + b₁) thence verify
SUBTRACTION
(i) closure property ( - )
when (a₁+b₁) ,(c₁ + d₁ ) ∈ ℂ
= (a₁+ b₁ )- (c₁ + d₁ )
=(a₁ - c₁) , (b₁ - d₁) ∈ ℂ (say closed - in complex number )
(ii) commutative property(- ):
when (a₁+b₁) ,(c₁ + d₁ ) ∈ ℂ
(a₁+b₁) -(c₁ + d₁ ) = (c₁ + d₁ ) - (a₁+b₁)
(a₁ -c₁) + (b₁- d₁) = (c₁ - a₁ ) +( d₁ - b₁)
(a₁ -c₁) + (b₁- d₁) = (c₁ - a₁ ) +( d₁ - b₁) NOT HOLD COMMUTATiVE
(iii) associative property ( - ):
once (a₁+b₁) , (c₁ ,d₁ ) , (e₁ , f₁ ) ∈ ℂ
[ ( (a₁+b₁) - (c₁ +d₁ ) ] - (e₁ + f₁ ).......1
= ( (a₁- c₁) - e₁ ( b₁ - d₁ ) - f₁
= [ a₁ - ( c₁+ e₁ ) , b₁ - ( d₁ + f₁ )
= (a₁ + b₁) -( c₁+ e₁ ) - ( d₁ + f₁)
= (a₁ + b₁) - [ ( c₁+ d₁ ) + ( e₁ + f₁) ]......2 NOT HOLD ( - )
MULTIPLICATION
(i ) closure property ( × )
when (a₁+b₁) ,(c₁ + d₁ ) ∈ ℂ
= (a₁+ b₁) . (c₁ + d₁ )
=(a₁ c₁ -b₁d₁ , a₁d₁ + b₁d₁ ) ∈ ℂ (say closed × in complex number )
(ii) ASSOCIATIVE PROPERTY ( × )
once (a₁+b₁) , (c₁ ,d₁ ) , (e₁ , f₁ ) ∈ ℂ
= [ (a₁+b₁) . (c₁ ,d₁ )] . (e₁ , f₁ )
= [ (a₁ c₁ -b₁d₁ , a₁d₁ + b₁c₁ ) ] . (e₁ , f₁ )
= [ (a₁ c₁ -b₁d₁ ) .e₁ - ( a₁d₁ + b₁d₁ ) . f₁ , (a₁ c₁ -b₁d₁) .f₁ +( a₁d₁ + b₁ c₁) . e₁ ]
= [ (a₁ c₁ e₁ - b₁d₁ e₁ - a₁d₁ f₁ - b₁d₁ f₁ , a₁ c₁f₁ -b₁d₁f₁+a₁d₁e₁ + b₁ c₁ e₁ )......1
= (a₁+b₁) [ (c₁ +d₁ ) . (e₁ + f₁ )]
= (a₁+b₁) [ (c₁e₁ - d₁ f₁) , ( c₁f₁ +d₁e₁ ) ]
= a₁ (c₁e₁ - d₁ f₁) - b₁ ( c₁f₁ +d₁e₁ ) , a₁ ( c₁f₁ +d₁e₁ ) e₁ +b₁ ( c₁ e₁ -d₁ f₁ )
=( a₁ c₁e₁ - a₁d₁ f₁ - b₁c₁f₁ - b₁ d₁e₁ , a₁ c₁f₁ + a₁ d₁e₁ + b₁ c₁ e₁ - b₁ d₁ f₁ ).....2
result 1 and 2 we get
[ (a₁ c₁ -b₁d₁ , a₁d₁ + b₁c₁ ) ] . (e₁ , f₁ ) = (a₁+b₁) [ (c₁e₁ - d₁ f₁) , ( c₁f₁ +d₁e₁ ) ]
MULTIPLICATIVE IDENTITY
∀ ( a₁ ,b₁) ∈ ℂ we have ( 1 , 0 ) ∈ ℂ
such that
( a₁ ,b₁) .(1 ,0 ) =( a₁ -0 ,0 +b₁ )
= ( a₁ ,b₁ )
this implies that (1 ,0 ) is multiplicative identity incomplex number
COMMUTATIVE PROPERTY ( × )
when (a₁+b₁) ,(c₁ + d₁ ) ∈ ℂ
(a₁+ b₁) . ( c₁+ d₁ ) = (c₁ + d₁ ) . (a₁+ b₁)
(a₁ c₁ -b₁d₁ , a₁d₁ + b₁c₁ ) = (c₁a₁ - d₁b₁ ,c₁b₁ +d₁a₁ )
as a result of multiplication is commutative in R
thens prove (a₁+ b₁) . ( c₁+ d₁ ) = ( c₁+ d₁ ).(a₁+ b₁)
∈ ℂ (say commutative in complex number )
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