Infinite Limit Complex Function

  1. 1. The problem statement, all variables and given/known data
    Find the limit of a complex number involving infinity.

    2. Relevant equations
    Lim z->infiity of (8z^3+5z+2)

    3. The attempt at a solution
    I tried to split the problem into real and imaginary parts using z = x+iy, but I don't know how to deal with the z->infinity.

  2. jcsd
  3. I could be misreading the problem, but the real part and imaginary part of that equation will go to infinity as well no matter which you take.
  4. Dick

    Dick 25,913
    Science Advisor
    Homework Helper

    z->infinity means |z|->infinity. What can you say about lim |8z^3+5z+2|?
  5. HallsofIvy

    HallsofIvy 41,265
    Staff Emeritus
    Science Advisor

    Thanks, Dick. I was about to ask exactly what "z-> infinity" meant! In the complex plane there can be an infinite number of "infinities"!
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