Question

1.y=1/(x2+2x)求值域2.y=6-cos²x-4sinx求值域3.y=(1-x)/(2x+5)求值域

Answer 1

1.

y=1/(x2+2x)

x²+2x

=x²+2x+1-1

=(x+1)²-1>=-1

令a=(x+1)²-1

y=1/a

若-1