COMPLEX NUMBERS
Any number of the form a+bi is known as complex number where a & b are real numbers & i= √-1 , a is called real part & b is called imaginary part.
A complex number is generally denoted by z. If a is 0 then
z is purely imaginary & if b is 0 then z is purely real.
NOTE:
1) i = √-1
2) i² = -1
3) i³ = i² i =-1.i =-i
4) i⁴ =i³.i =-i.i =-i² =-(-1) =1
5) i⁵ = i⁴ .i =1.i =i
6) i⁶ =i⁵.i = i.i = i² = -1
7) i⁷ =i⁶ .i =-1. i =-i
8 ) i⁸ =i⁷.i =-i.i =- i² = -(-1)=1
9) i⁹ = i⁸.i = 1.i =i
10)i¹º =i⁹.i =i.i =i² = -1
& so on .
Read blog on Line & it's Equation
ALJEBRA OF COMPLEX NUMBERS
1) ADDITION : When two complex numbers
are added their sum is also a complex number.
eg.
if z₁=a₁+b₁i & z₂=a₂+b₂i then z₁+ z₂ is given by
z₁+ z₂ = (a₁+b₁i ) + (a₂+b₂i )
= (a₁+a₂) + (b₁+b₂)i
2) SUBTRACTION : When two complex
numbers are subtracted their difference is
also a complex number .
eg.
if z₁=a₁+b₁i & z₂=a₂+b₂i then z₁-z₂ is given by
z₁- z₂ = (a₁+b₁i ) - (a₂+b₂i )
= (a₁-a₂) + (b₁-b₂)i
2) MULTIPLICATION : When two complex numbers
are multiplied their multilication is also a complex number .
eg.
if z₁=a₁+b₁i & z₂=a₂+b₂i then z₁. z₂ is given by
z₁. z₂ = (a₁+b₁i ) . (a₂+b₂i )
= (a₁a₂-b₁b₂) + ( a₁b₂+b₂a₁)i
EQUALITY OF COMPLEX NUMBERS
Two complex numbers are said to be equal if
1)Their real parts are equal
2)Their imaginary parts are also equal.
eg. If z₁=a+bi & z₂=2+3i
z₁=z₂ if a+bi =2+3i i.e a=2 & b=3
CONJUGATE OF A COMPLEX NUMBER
Two complex numbers which are differ only in the sign of their imaginary parts are said to be conjugates of each other.
If z is complex number then it's conjugate is denoted by z .ie. z bar.
if 2+3i is given complex number the it's conjugate is given by 2-3i.
z conjugate z
2+3i 2-3i.
2-3i 2+3i
-2+3i -2-3i
-2-3i -2+3i
-3i +3i
+3i -3i
NOTE : 1)SUM &product of two complex conjugates are real.
2)difference of two complex conjugates are imaginary.
Read the blog on Pascal Triangle & FIBONACCI NUMBERS
MODULUS & ARGUMENTS
If z=a+bi is a complex number then modulus of z is given by r=√a²+b² .
Argument or amplitude of z is given by 𝛩=tan⊣(y/x)
i.e tan inverse of y/x
POLAR FORM OF A COMPLEX NUMBER
IF z=a+bi is a complex number then it's
polar form is given by z=r(cos𝛩+ i sin 𝛩)
EXPONENTIAL FORM OF A COMPLEX NUMBER
2) e⁻ⁱө =e raise to -iө =cos Ө-i sinӨ
3) eⁱӨ +e⁻ⁱө =2cosө
4) eⁱӨ - e⁻ⁱө =2isinө
DE MOIVRE'S THEOREM
2) if (cos Ө-i sinӨ)⁴ = (cos 4Ө-i sin4Ө)
3) if (cos Ө+i sinӨ)⁻⁴ = (cos 4Ө-i sin4Ө)
4) if (cos Ө-i sinӨ)⁻⁴ = (cos 4Ө+i sin4Ө)