f(x) = ax² + bx  + c,f(0) = c = 2
f(x+ 1) = a(x + 1)² + b(x+ 1) + c
f(x + 1) - f(x) = a[(x + 1) + x][(x + 1) - x]+b(x + 1 - x) = a(2x + 1) + b = 2ax + a + b = 2x + 3
2a = 2,a = 1,a + b = 3,b = 2
f(x) = x² + 2x + 2


f(x) = (x + 1)² + 1,對稱軸x = -1在[-3,4]內(nèi),頂點(-1,1)
4離對稱軸更遠,f(4) = 26
[=3,4]上的值域:[1,26]

對稱軸x = -1,f(x)向右平移一個單位時(x -> x -1),對稱軸為y軸,新拋物線為偶函數(shù),m = -1
f(m) = f(-1) = 1,f(f(-1)) = f(1) = 5


區(qū)間[m,m + 2]為[-1,1],f(x)為開口向上的拋物線,對稱軸x = -1在[-1,1]內(nèi),最小值為頂點的縱坐標1