1. Let three complex numbers $1, \mathrm{i}, z$ correspond to three collinear points in the complex plane, and $|z|=5$. Then $z=$ $\qquad$ .
$-、 1.4-3 \mathrm{i}$ or $-3+4 \mathrm{i}$.
Let $z=x+y \mathrm{i}$.
From the problem, we get $x+y=1$, and $x^{2}+y^{2}=25$. Therefore, $(x, y)=(4,-3)$ or $(-3,4)$.