2. If $a, b, c$ are given distinct real numbers, then the algebraic expression $f(x)=\frac{a^{2}(x-b)(x-c)}{(a-b)(a-c)}+\frac{b^{2}(x-c)(x-a)}{(b-c)(b-a)}+\frac{c^{2}(x-a)(x-b)}{(c-a)(c-b)}$ simplifies to $\qquad$
Since $f(a)=a^{2}, f(b)=b^{2}, f(c)=c^{2}$, and $f(x)$ is a polynomial function of degree no higher than two, we have $f(x)=x^{2}$.

