Excellent work!
Your calculations are correct, but near the end, you have forgotten to cancel u. If you cancel the u, the linear term becomes a constant, and the resultant equation becomes a simple quadratic which is much easier to solve.
I get u=7.468 m/s using g=9.81 (as you did)
You will rework and should get 7.468 m/s as well.
Congrats for the good work!
Your calculations are correct, but near the end, you have forgotten to cancel u. If you cancel the u, the linear term becomes a constant, and the resultant equation becomes a simple quadratic which is much easier to solve.
I get u=7.468 m/s using g=9.81 (as you did)
You will rework and should get 7.468 m/s as well.
Congrats for the good work!