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

Toán Lớp 11: Tìm nghiệm nhỏ nhất 2sin(4x-pi/3)-1=0 a. x=pi/4 b.x=7pi/24 c=pi/8 d.x=pi/12

Tháng Một 13, 2023 Toán học 2 Comments 0 views

Toán Lớp 11: Tìm nghiệm nhỏ nhất 2sin(4x-pi/3)-1=0
a. x=pi/4 b.x=7pi/24
c=pi/8 d.x=pi/12

Comments ( 2 )

  1. aivilanlan
    aivilanlan
    13 Tháng Một, 2023 at 3:59 chiều
    Reply
    2sin(4x-π/3)=1
    <=>sin(4x-π/3)=1/2
    <=>\(\left[ \begin{array}{l}4x-\dfrac{π}{3}=\dfrac{π}{6}+k2π\\4x-\dfrac{π}{3}=\dfrac{5π}{6}+k2π\end{array} \right.\)
    <=>\(\left[ \begin{array}{l}x=\dfrac{π}{8}+k\dfrac{π}{2}\\x=\dfrac{7π}{24}+k\dfrac{π}{2}\end{array} \right.\) 
    =>C

  2. hienchaudiem
    hienchaudiem
    13 Tháng Một, 2023 at 3:59 chiều
    Reply
    ~rai~
    \(2\sin\left(4x-\dfrac{\pi}{3}\right)-1=0\\\Leftrightarrow \sin\left(4x-\dfrac{\pi}{3}\right)=\dfrac{1}{2}\\\Leftrightarrow \left[\begin{array}{I}4x-\dfrac{\pi}{3}=\dfrac{\pi}{6}+k2\pi\\4x-\dfrac{\pi}{3}=\pi-\dfrac{\pi}{6}+k2\pi\end{array}\right.\\\Leftrightarrow \left[\begin{array}{I}4x=\dfrac{\pi}{2}+k2\pi\\4x=\dfrac{7\pi}{6}+k2\pi\end{array}\right.\\\Leftrightarrow \left[\begin{array}{I}x=\dfrac{\pi}{8}+k\dfrac{\pi}{2}\\x=\dfrac{7\pi}{24}+k\dfrac{\pi}{2}.\end{array}\right.\quad(k\in\mathbb{Z})\\\text{Nghiệm nhỏ nhất:}\dfrac{\pi}{8}+0.\dfrac{\pi}{2}=\dfrac{\pi}{8}.\\\to\text{Chọn ý C.}\)
     

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

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