# finding the minimum

#### Extractiful

hi, i wanted to know how do i get the minimum for $$\displaystyle \displaystyle f(x)=\sum_{i=1}^k\|x-a_i\|^2$$ where $$\displaystyle f:\mathbb R^n\to\mathbb R$$ and $$\displaystyle a_1,\ldots,a_k\in\mathbb R^n.$$