Quadratic Question

Hi for school we recieved a question in which we needed to show that the x-coordinate of the vertex of the graph of y=ax^2 + bx + c is x=-b/2a

Any help would be appreciated.

Thanks

Use the first derivate

f(x)= ax^2 + bx + c
f'(x)= 2ax + b

A Vertex can be found where f'(x)=0

0= 2ax + b
-b/2a = x