ABSOLUTE VALUE OF A COMPLEX NUMBER

The absolute value of a complex number, a + ib (also called the modulus ) is defined as the distance between the origin (0, 0) and the point (a, b) in the complex plane.

To find the absolute value of a complex number, we have to take square root of the sum of squares of real and part imaginary part respectively.

|a + ib| = √(a2 + b2)

Example 1 :

Find the absolute value of 7 - i.

Solution :

|7 - i|  =  √[72 + (-1)2]

=  √(49 + 1

=  √50

=  √(5 x 5 x 2)

=  5√2

Example 2 :

Find the absolute value of -5 - 5i.

Solution :

|-5 - 5i|  =  √[(-5)2 + (-5)2]

=  √(25 + 25) 

=  √50

=  √(5 x 5 x 2)

=  5√2

Example 3 :

Find the absolute value of 3 - 6i.

Solution :

|3 - 6i|  =  √[32 + (-6)2]

=  √(9 + 36) 

=  √45

=  √(3 x 3 x 5)

=  3√5

Example 4 :

Find the absolute value of 10 - 2i.

Solution :

|10 -2i|  =  √[102 + (-2)2]

=  √(100 + 4) 

=  √104

=  √(2 x 2 x 26)

=  2√26

Example 5 :

Find the absolute value of -4 - 8i.

Solution :

|-4 - 8i|  =  √[(-4)2 + (-8)2]

=  √(16 + 64) 

=  √80

=  √(2 x 2 x 2 x 2 x 5)

= 4√5

Example 6 :

Find the absolute value of -4 + 10i.

Solution :

|-4 + 10i|  =  √[(-4)2 + 102]

=  √(16 + 100)

=  √116

=  √2 x 2 x 29 = 2 √29

Example 7 :

Find the absolute value of 1 - 8i.

Solution :

|1 - 8i|  =  √[12 + (-8)2]

=  √(1 + 64)

=  √65

Example 8 :

Find the absolute value of -4 - 3i.

Solution :

|-4 - 3i|  =  √(-4)2 + (-3)2

=  √(16 + 9) 

=  √25

=  5 

Example 9 :

Find the absolute value of -1 + 5i.

Solution :

|-1 + 5i|  =  √[(-1)2 + 52]

=  √(1 + 25) 

=  √26

Example 10 :

Find the absolute value of 8 - 3i.

Solution :

|8 - 3i|  =  √[82 + (-3)2]

=  √(64 + 9) 

=  √73

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