下列函数哪些是非周期函数（ ）。
A: x (t)= cos8ω0t ，
B: x (t)= cosω0+cos2ω0t
C: x (t)= sinω0t+sinω0t
D: x (t)=sin3ω0t
A: x (t)= cos8ω0t ，
B: x (t)= cosω0+cos2ω0t
C: x (t)= sinω0t+sinω0t
D: x (t)=sin3ω0t
举一反三
- 下列函数哪些是非周期函数（ ）。 A: x (t)=sin3ω0t B: x (t)= cos8ω0t ， C: x (t)= sinω0t+sin<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202012/d10869ee2b304465a617ab660744efff.png">ω0t D: x (t)= cosω0+cos2ω0t
- 曲线$\left\{ \matrix{ {x^2} + {y^2} + {z^2} = 9 \cr y = x \cr} \right.$的参数方程为( ). A: $$\left\{ \matrix{ x = \sqrt 3 \cos t \cr y = \sqrt 3 \cos t \cr z = \sqrt 3 \sin t \cr} \right.(0 \le t \le 2\pi )$$ B: $$\left\{ \matrix{ x = {3 \over {\sqrt 2 }}\cos t\cr y = {3 \over {\sqrt 2 }}\cos t \cr z = 3\sin t \cr} \right.(0 \le t \le 2\pi )$$ C: $$\left\{ \matrix{ x = \cos t\cr y = \cos t\cr z = \sin t \cr} \right.(0 \le t \le 2\pi )$$ D: $$\left\{ \matrix{ x = {{\sqrt 3 } \over 3}\cos t\cr y = {{\sqrt 3 } \over 3}\cos t \cr z = {{\sqrt 3 } \over 3}\sin t\cr} \right.(0 \le t \le 2\pi )$$
- 下列函数是奇谐函数的是？ A: x(t)=sin(3t+2)+1 B: x(t)=cos(t+2) C: x(t)=sin(t)+2 D: x(t)=cos(2t+1)
- 下列傅里叶变换错误的是（） A: 1←→2πδ（ω） B: ejω0t←→2πδ（ω–ω0） C: cos（ω0t）←→π[δ（ω–ω0）+δ（ω+ω0）] D: sin（ω0t）=jπ[δ（ω+ω0）+δ（ω–ω0）]
- 设\(z = {e^{x - 2y}}\)，而\(x = \sin t\)，\(y = {t^3}\)，则全导数\( { { dz} \over {dt}} = \) A: \({e^{\sin t - {t^3}}}(\cos t - 6{t^2})\) B: \({e^{\sin t - 2{t^3}}}(\sin t - 6{t^2})\) C: \({e^{\cos t - 2{t^3}}}(\cos t - 6{t^2})\) D: \({e^{\sin t - 2{t^3}}}(\cos t - 6{t^2})\)