令x+1=t ,则x=t-1回代：3(t-1)-1=3t-3-1=3t-4∴f(x)=3x-41.f(sinx+cosx)=3(sinx+cosx)-4=3sinx+3cosx-42.f(sinx+cosx)=3sinx+3cosx-4=(√3²+3²)×sin(x + π/4) - 4=(3√2)sin(x + π/4) - 4T=2π/1 =2π3...