y=f(x)+f(x+2)
=2sin(π/4x+π/4)+2sin[π/4(x+2)+π/4]
=2sin(π/4x+π/4)+2sin(π/4 x+3π/4)
=2sin(π/4x+π/4)+2sin(π/4-π/4x)
展开,化简得
=2√2cos(π/4 x)
∵ -6≤x≤-2/3
∴ -3π/2≤π/4 x≤-π/6
∴ π/4 x=-π/6,即x=-2/3时,f(x)有最大值2√2*(√3/2)=√6
π/4 x=-π,即x=-4时,f(x)有最小值2√2*(-1)=-2√2
y=f(x)+f(x+2)
=2sin(π/4x+π/4)+2sin[π/4(x+2)+π/4]
=2sin(π/4x+π/4)+2sin(π/4 x+3π/4)
=2sin(π/4x+π/4)+2sin(π/4-π/4x)
展开,化简得
=2√2cos(π/4 x)
∵ -6≤x≤-2/3
∴ -3π/2≤π/4 x≤-π/6
∴ π/4 x=-π/6,即x=-2/3时,f(x)有最大值2√2*(√3/2)=√6
π/4 x=-π,即x=-4时,f(x)有最小值2√2*(-1)=-2√2