• 2022-06-04 问题

    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: \({e^{\sin t - 2{t^3}}}(\cos t - 6{t^2})\)

    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: \({e^{\sin t - 2{t^3}}}(\cos t - 6{t^2})\)

  • 2022-06-09 问题

    设\(z = {e^{x - 2y}}\),而\(x = \sin t,\;y = {t^3},\)则\( { { dz} \over {dt}} = \)( ) A: \({e^{\sin t - 2{t^3}}}\) B: \({e^{\sin t - 2{t^3}}}\left( {\cos t - 6{t^2}} \right)\) C: \({e^{\sin t - 2{t^3}}}\ {\sin t } \) D: \({e^{\sin t - 2{t^3}}}\,{t^3}\)

    设\(z = {e^{x - 2y}}\),而\(x = \sin t,\;y = {t^3},\)则\( { { dz} \over {dt}} = \)( ) A: \({e^{\sin t - 2{t^3}}}\) B: \({e^{\sin t - 2{t^3}}}\left( {\cos t - 6{t^2}} \right)\) C: \({e^{\sin t - 2{t^3}}}\ {\sin t } \) D: \({e^{\sin t - 2{t^3}}}\,{t^3}\)

  • 2021-04-14 问题

    级数sin(π/6)+sin(2π/6)+sin(3π/6)+…收敛

    级数sin(π/6)+sin(2π/6)+sin(3π/6)+…收敛

  • 2022-06-19 问题

    求微分方程[img=261x61]17da6536c0cca5d.png[/img]的通解; ( ) A: C18*cos(t) - C20*sin(t) - C19*t*cos(t) - C21*t*sin(t) B: C18*cos(t) + C20*sin(t) - C19*t*cos(t) - C21*t*sin(t) C: C18*cos(t) + C20*sin(t) + C19*t*cos(t) + C21*t*sin(t) D: -C18*cos(t) + C20*sin(t) + C19*t*cos(t) + C21*t*sin(t)

    求微分方程[img=261x61]17da6536c0cca5d.png[/img]的通解; ( ) A: C18*cos(t) - C20*sin(t) - C19*t*cos(t) - C21*t*sin(t) B: C18*cos(t) + C20*sin(t) - C19*t*cos(t) - C21*t*sin(t) C: C18*cos(t) + C20*sin(t) + C19*t*cos(t) + C21*t*sin(t) D: -C18*cos(t) + C20*sin(t) + C19*t*cos(t) + C21*t*sin(t)

  • 2022-06-12 问题

    理想低通滤波器频响特性系统响应为()。 A: sin(πt) B: sinc(2πt) C: sinc(6πt) D: sinc(5πt)

    理想低通滤波器频响特性系统响应为()。 A: sin(πt) B: sinc(2πt) C: sinc(6πt) D: sinc(5πt)

  • 2022-06-07 问题

    下列信号中,( )信号的频谱是连续的。 A: $x(t) = A\sin (\omega t + {\varphi _1}) + B\sin (3\omega t + {\varphi _2})$ B: $x(t) = 5\sin 30t + 3\sin \sqrt {50} t$ C: $x(t) = {e^{ - at}}\sin {\omega _0}t$

    下列信号中,( )信号的频谱是连续的。 A: $x(t) = A\sin (\omega t + {\varphi _1}) + B\sin (3\omega t + {\varphi _2})$ B: $x(t) = 5\sin 30t + 3\sin \sqrt {50} t$ C: $x(t) = {e^{ - at}}\sin {\omega _0}t$

  • 2022-05-30 问题

    信号x(t) = sin(t)+sin(√2.t),是一个周期信号

    信号x(t) = sin(t)+sin(√2.t),是一个周期信号

  • 2022-06-07 问题

    (1-sin^6α-cos^6α)/(sin^2α-sin^4α)的值

    (1-sin^6α-cos^6α)/(sin^2α-sin^4α)的值

  • 2022-05-30 问题

    x=tan(t)sin(t)-cos(t)=?

    x=tan(t)sin(t)-cos(t)=?

  • 2022-06-09 问题

    ‏已知函数[img=102x27]18030256dad01f2.png[/img],求其三阶导数,下面命令正确的是()‍ A: syms t; G=simplify(diff(t^2*sin(t),t,3)) B: syms t; G=simplify(int(t^2*sin(t),t,3)) C: syms t; G=simplify(diff(t^2*sin(t),t)) D: syms t; G=simplify(int(t^2*sin(t),t))

    ‏已知函数[img=102x27]18030256dad01f2.png[/img],求其三阶导数,下面命令正确的是()‍ A: syms t; G=simplify(diff(t^2*sin(t),t,3)) B: syms t; G=simplify(int(t^2*sin(t),t,3)) C: syms t; G=simplify(diff(t^2*sin(t),t)) D: syms t; G=simplify(int(t^2*sin(t),t))

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