1.y=√(x+1)-2x (x>=-1)
移项
y+2x=√(x+1)
两边平方
y^2+4xy+4x^2=x+1
4x^2+(4y-1)x+y^2-1=0
△=(4y-1)^2-4*4(y^2-1)>=0
-8y+17>=0
则值域y