求函数f(x)=x^2-2ax+3(1≤x≤2)的最小值

求函数f(x)=x^2-2ax+3(1≤x≤2)的最小值f(x) = x^2 - 2ax + 3= x^2 - 2ax + [(-2a)/2]^2 - [(-2a)/2]^2 + 3= (x - a)^2 - a^2 + 3f(x)min = -a^2 + 3(x = a时)-4 + 3≤f(x)min≤-1 + 3-1≤f(x)min≤2f(x)min≥-1