# what is magnitude of −3i?

Relevance
• The magnitude is 3.

• Login to reply the answers
• √(0^2 + (-3)^2) =

√(0 + 9) =

√9 =

3

• Login to reply the answers
• -

Magnitude is 3

• Login to reply the answers
• |-3i| = |-3| x |i| = 3 x 1 = 3.

• Login to reply the answers
• The magnitude is '3' usuallu written as |3|.

• Login to reply the answers
• Anonymous
11 months ago

(-3)^2 = 9. Don't listen to the idiots who says it's 3.

• The first equation is true, but the "magnitude" of a vector is the absolute value of its length, so 3 is actually correct.

• Login to reply the answers
• i is the square root of -1. so you'll have to square both of these. In this example: -3*-3 =9 and sqrt(-1)*sqrt(-1) =-1 . So now take 9*-1 to get a final answer of -9

• Login to reply the answers
• Remember:

|a + bi| = √(a² + b²)

In this case, a=0, b=-3

|-3i| = √[(-3)²]

= √9

= 3

Of course if you think of it as the distance from the origin (0,0i) to (0,-3i) on the complex plane, it's obviously just 3, as confirmed by the formula.

• Login to reply the answers
• It is just 3.

Use pythagoras to find the hypotenuse and ie. the longest side which is the magnitude when you have numbers in both vertical and horizontal components, like -3i+2j.

Also the magnitude is just the positive value of the length of the line/vector, just thought i'd mention.

• Login to reply the answers
• 3

.....................

• Login to reply the answers