Question 416300
t^2+2t-9=0 
Since you can't factor, you must resort to the "quadratic formula".
Doing so yields:
t = {2.162, -4.162}
You can throw out the negative solution leaving:
t = 2.12 seconds
.
Details of quadratic follows:
.
*[invoke quadratic "t", 1, 2, -9 ]