Step-by-step:
1. Identify the coefficients a and b (a=1/2, b=2)
2. Then put those numbers in the vertex formula which is x= -b/2a (-2/2*1/2)
3. Solve for x (x= -2)
4. Find the y-coordinate of the vertex by plugging in x= -2 (y= 1/2(-2)^2+2(-2)- 3)
5. Calculate all of that (y= -5)
6. Put those to coordinates together (Remember: x= -2, y= -5)
7. So your vertex would be (-2, -5)
I hope that made sense ☺️!