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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 11: giải phương trình: sin (x/2-pi/3) =-căn3/2

Toán Lớp 11: giải phương trình: sin (x/2-pi/3) =-căn3/2

Comments ( 2 )

  1. sin(x/2-π/3)=-\sqrt{3}/2
    ⇔sin(x/2-π/3)=sin(-π/3)
    ⇔ $\left[\begin{matrix} \dfrac{x}{2}-\dfrac{π}{3}=-\dfrac{π}{3}+k2π\\\dfrac{x}{2}-\dfrac{π}{3}=π+\dfrac{π}{3}+k2π\end{matrix}\right.$
    ⇔ $\left[\begin{matrix} \dfrac{x}{2}=\dfrac{π}{3}-\dfrac{π}{3}+k2π\\\dfrac{x}{2}=\dfrac{π}{3}+π+\dfrac{π}{3}+k2π\end{matrix}\right.$
    ⇔ $\left[\begin{matrix}\dfrac{x}{2}=k2π\\\dfrac{x}{2}=\dfrac{5π}{3}+k2π\end{matrix}\right.$
    ⇔ $\left[\begin{matrix}x=k4π\\x=\dfrac{10π}{3}+k4π\end{matrix}\right.$
    $\text{Vậy phương trình có 2 họ nghiệm}$
    $\left[\begin{matrix}x=k4π\\x=\dfrac{10π}{3}+k4π\end{matrix}\right.$

  2. Giải đáp + Lời giải và giải thích chi tiết:
    sin(x/2-pi/3)=-sqrt3/2
    <=>sin(x/2-pi/3)=sin(-pi/3)
    <=>\(\left[ \begin{array}{l}\dfrac{x}{2}-\dfrac{\pi}{3}=-\dfrac{\pi}{3}+k2\pi\\\dfrac{x}{2}-\dfrac{\pi}{3}=\pi+\dfrac{\pi}{3}+k2\pi\end{array} \right.\)
    <=>\(\left[ \begin{array}{l}\dfrac{x}{2}=k2\pi\\\dfrac{x}{2}=\dfrac{5\pi}{3}+k2\pi\end{array} \right.\)
    <=>\(\left[ \begin{array}{l}x=k4\pi\\x=\dfrac{10\pi}{3}+k4\pi\end{array} \right.\)(kinZZ)

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222-9+11+12:2*14+14 = ? ( )