Shivam D.

asked • 09/23/14

complex number

If mod z =2, then the points representing the complex numbers -1+5z will lie on a??
1. circle
2. straight line
3. parabola
4. ellipse

1 Expert Answer

By:

Josh W. answered • 09/23/14

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Shivam D.

first 2 lines are clear but i didn't get the remaining..please explain
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09/23/14

Josh W.

When we think about complex functions like -1+5z, its important to notice what this represents mathematically in correlation with mod z=2. 
 
The modulus of a complex number is it's distance to the origin on the complex plane. So, by the Pythagorean theorem, x2+y2=22. The complex numbers that satisfy this condition lie on a circle with a radius of 2 units. 
 
Now, in relation to Algebra II, when we make linear alterations to a function, the type of shape does not change. Only the position. So, given a complex number lying on that radius-2 circle, the function -1+5z would look like this:
-1+5x+i5y. When graphed, the overall shape of the graph doesn't change. Only the position changes. 
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09/25/14

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