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

Toán Lớp 11: y=sinx -(sinx- $\pi$ /6), Tìm max-min

Toán Lớp 11: y=sinx -(sinx- $\pi$ /6), Tìm max-min

Comments ( 2 )

  1. Giải đáp:
     
    Lời giải và giải thích chi tiết:
    Ta có $: – 1 ≤ cos(x – \dfrac{π}{12}) ≤ 1$
    $ y = sinx – sin(x – \dfrac{π}{6}) = 2cos(x – \dfrac{π}{12}).sin\dfrac{π}{12}$
    $ ⇒ – 2sin\dfrac{π}{12} ≤ y ≤ 2sin\dfrac{π}{12}$
    Vậy :
    $ Miny = – 2sin\dfrac{π}{12} ⇔ cos(x – \dfrac{π}{12}) = 1$
    $ ⇔ x – \dfrac{π}{12} = (2k + 1)π ⇔ x = \dfrac{π}{12} + (2k + 1)π $
    $ Maxy = 2sin\dfrac{π}{12} ⇔ cos(x – \dfrac{π}{12}) = 1$
    $ ⇔ x – \dfrac{π}{12} = 2kπ ⇔ x = \dfrac{π}{12} + 2kπ $
     

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

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