∵y=(√6∕4)sinx-(√2/4)cosx =(√2/4)[√3sinx-cosx] =(√2/2)[(√3/2)sinx-(1/2)cosx] =(√2/2)[sinπ/3sinx-(cosπ/3)cosx] =(-√2/2)cos(x+π/3) π/6≤x≤2π/3 ∴π/2≤x+π/3≤π ∴-√2/2≤y≤0
