Question 1011576
Enter the equation under Y=
use window -5<=x<=5
-10<=y<=10
scl 1
see what looks like a clear root at 1
Check that 2+5-1-6=0
(x-1) is a factor.
The other root is near -2.  Check f(-2):-16+20+2-6
There is a third root that is not an integer.
divide x-1 into 2x^3+5x^2-x-6;
synthetic division
1/2==5==-1==-6
2===7==6===0
so the second factor is (2x^2+7x+6)
This factors into (2x+3)(x+2);  function's factors are (x-1)(2x+3)(x+2)
roots are -2 and -1.5.
One can change the window to look at x between -1 and -2.
Use 2nd Trace to get calc, and 2 for zero.  Put the cursor below the x-axis near where the function climbs above.  Left bound: Enter.  Move it to the right side and hit Enter for right bound.  When Guess appears on screen, hit enter, and -1.5 will appear.
{{{graph(300,200,-5,5,-10,10,2x^3+5x^2-x-6)}}}