若实数x,y满足x^2/4+y^2/3=1,则x+2y的取值范围是

实数x,y满足x^2/4+y^2/3=1
设x=2cost
y=√3sint
则
x+2y
=2cost+2√3sint
=4(1/2*cost+√3/2sint)
=4(cos60*cost+sin60sint)
=4cos(60-t)
=4cos(t-60)
因为-1