Diagram shows the curve of a quadratic function $\displaystyle f(x) = ax^2 + bx + c$, where $\displaystyle a$, $\displaystyle b$ and $\displaystyle c$ are constant.

a)find the value of $\displaystyle a$,$\displaystyle b$ and $\displaystyle c$

b)Determine the range value of $\displaystyle x$ if $\displaystyle f(x) \geq 1$