1
f(x)=3cos2x
f(-x)=3cos(-2x)=3cos2x=f(x)
f(x)是偶函数
2
f(x)=cos(3/4x+3π/2)=sin(3/4x)
f(-x)=sin(-3/4x)=-sin(3/4x)=-f(x)
f(x)是奇函数
1
f(x)=3cos2x
f(-x)=3cos(-2x)=3cos2x=f(x)
f(x)是偶函数
2
f(x)=cos(3/4x+3π/2)=sin(3/4x)
f(-x)=sin(-3/4x)=-sin(3/4x)=-f(x)
f(x)是奇函数