Answer
$k\le0$, $(h\pm\sqrt {-\frac{k}{a}},0)$
Work Step by Step
Step 1. For at least one x-intercept, we need $(x-h)^2=-\frac{k}{a}\ge0$ which gives $k\le0, \ (a\gt0)$.
Step 2. For x-intercepts, we have $(x-h)^2=-\frac{k}{a}$, thus $x=h\pm\sqrt {-\frac{k}{a}}$ or $(h\pm\sqrt {-\frac{k}{a}},0)$
