exam Maths Puzzle Numerical Ability

I am confused. o.k. the problem is xsquared+7x+9=0 i do not get how to find the vertex . i know it has to do with the it being max or miminmum . right ?
Thanks for the help !!
- confused

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exam Other Question

Divide.
x^2-49y^2/6x^2+42y divided by (x^2-7xy)
2+ radical 3 / radical 3+ radical 5