Using a TI-84+, enter the equation using the Y= key
Press the GRAPH key.
Press 2nd and then the TRACE key to bring up the CALC menu.
Choose 2: zero
Using the left arrow key, move the 'spider' to just above the left x-intercept and press ENTER to mark the left bound side of your zero, then move the spider just below the x-intercept and press ENTER to mark the right bound side of your zero. Press ENTER once more to reveal the zero (x-intercept).
You should've gotten -.6513878
That's rounded off, because the exact answer is irrational. Use the quadratic formula to verify this.
You need to repeat this process for the other zero.
By the way, the spider is that blinking asterisk of a thing that is tracing the curve when you use the left or right arrow keys.