The modulus of a complex number z = a + ib is given by:
A
√(a² + b²)
B
a + b
C
√(a² - b²)
D
a² + b²
Analysis & Theory
The modulus of z = a + ib is |z| = √(a² + b²).
The conjugate of a complex number z = a + ib is:
A
a - ib
B
a + ib
C
-a + ib
D
-a - ib
Analysis & Theory
The conjugate of z = a + ib is ȳ = a - ib.
If z = a + ib, then |z|² equals:
A
z * z̅
B
z + z̅
C
z - z̅
D
z / z̅
Analysis & Theory
|z|² = (a + ib)(a - ib) = a² + b² = z * z̅.
The product of a complex number and its conjugate is always:
A
A non-negative real number
B
A purely imaginary number
C
A complex number with non-zero imaginary part
D
Zero
Analysis & Theory
z * z̅ = a² + b², which is always a non-negative real number.
The conjugate of a sum of two complex numbers z₁ and z₂ is:
A
z̅₁ + z̅₂
B
z₁ + z₂
C
z̅₁ - z̅₂
D
-z̅₁ - z̅₂
Analysis & Theory
Conjugate distributes over addition: (z₁ + z₂)̅ = z̅₁ + z̅₂.
The conjugate of a product of two complex numbers z₁ and z₂ is:
A
z̅₁ * z̅₂
B
z₁ * z₂
C
z̅₁ + z̅₂
D
z₁ / z₂
Analysis & Theory
Conjugate distributes over multiplication: (z₁ * z₂)̅ = z̅₁ * z̅₂.
If z = a + ib, then 1/z can be written as:
A
z̅ / |z|²
B
|z| / z̅
C
z / |z|²
D
z̅ / |z|
Analysis & Theory
1/(a + ib) = (a - ib)/(a² + b²) = z̅ / |z|².
The modulus of the conjugate of a complex number z is:
A
|z|
B
-|z|
C
1/|z|
D
|z|²
Analysis & Theory
|z̅| = |a - ib| = √(a² + b²) = |z|.
If z + z̅ = 10, then z is necessarily:
A
A real number
B
A purely imaginary number
C
A complex number with non-zero imaginary part
D
Zero
Analysis & Theory
z + z̅ = 2a ⇒ a = 5, so z = 5 + ib, real part exists. If imaginary part is 0, z is real.
If z - z̅ = 6i, then the imaginary part of z is:
A
3
B
6
C
0
D
Undefined
Analysis & Theory
z - z̅ = 2ib = 6i ⇒ b = 3, so imaginary part is 3.