Answer
$[-3,\frac{1}{2}]$
Work Step by Step
Step 1. Graph the function $f(x)=2x^2+5x-3$ as shown in the figure.
Step 2. The zeros of the function can be identified as $x=-3,\frac{1}{2}$
Step 3. We can identify the regions where $f(x)\leq0$ as $[-3,\frac{1}{2}]$
