f(x)=x^2-2x+3=（x-1)^2+2
函數(shù)在1處最小,左側(cè)減少,右側(cè)增加.
當(dāng)1 在[t,t+1]內(nèi)時,即0<=t<=1時,g(t）=2
當(dāng)t>1,f(x)在[t,t+1]上增加,g(t)=t^2-2^t+3
當(dāng)t<0,f(x)在[t,t+1]上減少,g(t)=（t+1）^2-2^（t-1）+3=t^2+2