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Randy B. | Algebra, Prealgebra, Precalculus, Geometry, Mathematics, ReadingAlgebra, Prealgebra, Precalculus, Geomet...
4.8 4.8 (13 lesson ratings) (13)
    -5 + 4i
- (-2  - 5i ) note :  I distribute the -1 through the parenthesis
   -5 + 4i
  +2 + 5i  Note:  Add like terms
  -3  + 9i   note:   same answer as above
                         I used vertical format, which is the way I would do the problem
                          with paper and pencil.  :)  Randy Brown
John M. | College Student for Math tutoringCollege Student for Math tutoring
"i" is considered "imaginary" as the square root of -1 does not exist. So you just add/subtract the real numbers and the imaginary separately. 
Thus: (-5+4i)-(-2-5i)=(-5-(-2))+(4i-(-5i))=(-5+2)+(4i+5i)=-3+9i