Interpolate f at the points $x-h , x $ and $x+h$ by a quadratic polynomial $p(x)$

Question

Interpolate f at the points $x-h , x$ and $x+h$ by a quadratic polynomial $p(x)$.

Let $ \ p(x)=a+bx+cx^{2} \ $. Now,\begin{align} p(x-h)=f(x-h)=a+b(x-h)+c(x-h)^{2}, \\p(x)=f(x)=a+bx+cx^{2} , \\ p(x+h)=f(x+h)=a+b(x+h)+c(x+h)^{2}, \end{align}

But now this is tedius to find out the constants $a, b, c$.

Any help please.