Prove that $$ \lim_{z\to i} \dfrac{3z^4-2z^3+8z^2-2z+5}{z-i} = 4+4i $$
2026-04-13 09:45:05.1776073505
Limit concept under Complex analysis
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Hint: The number $i$ is a root of both the denominator and the numerator. Since the numerator is a polynomial with real coefficients, it follows that $-i$ is also a root of the polynomial, which means that you can factor out $z^2+1$ on the numerator, which should be easier than factoring out $z-i$.