紧急求助!高一数学题

f(x)=(3/2)*sin2x-2cosx-2
=√[(3/2)^2+(-2)^2]*sin(2x+a)-2
其中tana=(-2)/(3/2)=-4/3

所以f(x)最大值=√[(3/2)^2+(-2)^2]-2
=1/2

f(x)=3sinxcosx-4cosx
=3/2(sin2x)-4cosx
最大值为根号下9/4+16=根73/2

f(x)=3/2*sin2x-4(cos2x+1)/2
=3/2*sin2x-2cos2x-2
=(3/2)^2+2^2-2=17/4

1/2