Solve: 

Since this equation is set equal to zero, the zeros (roots) will be the locations where the graph crosses the x-axis (if the roots are real numbers).
1.  Set f (x) = x² - 5x - 14

2.  Engage the ZERO command: 
, #6 Analyze Graph, #1 Zero

(lower bound) Move "pointing hand" to the left of intersection point (where the graph crosses the x-axis), and click. This will lock a location on the left of the intersection.

(upper bound) Move the hand to the right side of the intersection, and click. The right boundary will appear and the intersection point will be labeled.

3.  Repeat the entire process for the second zero (root).

4. Both zeros (or roots) appear.

Window has been adjusted to
[x: 10 to -10] and [y: 5 to - 25]