1. Let $a, b$ be unequal real numbers. If the quadratic function $f(x)=x^{2}+a x+b$ satisfies $f(a)=f(b)$, then $f(2)=$ _
Answer: 4. Solution: From the given conditions and the axis symmetry of the quadratic function graph, we get $\frac{a+b}{2}=-\frac{a}{2}$, which means $2 a+b=0$, so $f(2)=4+2 a+b=4$.