This is LaTeX code:

[latex]
p\left( {x + a} \right) = \sum\limits_{i = 0}^n {a_i \left( {x + a} \right)^i } = \sum\limits_{i = 0}^{n - 1} {a_i \left( {x + a} \right)^i } + a_n \left( {x + a} \right)^n
[/latex]