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

Toán Lớp 7: 1) Tìm x biết a) (x-1)^2023 = (x-1)^2021 b) x-5-1/3 = 3.x/4+1/5

Tháng Hai 3, 2023 Toán học 2 Comments 0 views

Toán Lớp 7: 1) Tìm x biết
a) (x-1)^2023 = (x-1)^2021
b) x-5-1/3 = 3.x/4+1/5

Comments ( 2 )

  1. myngocla
    myngocla
    3 Tháng Hai, 2023 at 7:01 sáng
    Reply
    a, (x-1)^{2023} = (x-1)^{2021}
    Để (x-1)^{2023} = (x-1)^{2021} thì :
    Ta có : (x-1) = ±1 hoặc = 0
    ⇒ x -1 = 1 ⇔ x = 2
    ⇒ x – 1 = -1 ⇔ x = 0
    ⇒ x – 1 = 0 ⇔ x = 1
     b, x – 5 – \frac{1}{3} =\frac{3x}{4} + \frac{1}{5}
    ⇒ x – 5 – \frac{3x}{4} = \frac{1}{3} + \frac{1}{5}
    ⇒ x – 5 – \frac{3x}{4} = \frac{8}{15}
    ⇒ x – \frac{3x}{4}  = \frac{8}{15} + 5 = \frac{83}{15}
    ⇒ \frac{x}{4} = \frac{83}{15}
    ⇒ x . 15 = 4 . 83
    ⇒ x = \frac{332}{15}
                                               XIN HAY NHẤT NHA

  2. hoquyly
    hoquyly
    3 Tháng Hai, 2023 at 7:00 sáng
    Reply
    \text{a)}
    (x-1)^2023 = (x-1)^2021
    -> (x-1)^2023 – (x-1)^2021 = 0
    -> (x-1)^2021[ (x-1)^2 – 1 ] = 0 
    ->  \(\left[ \begin{array}{l}(x-1)^{2021} =0\\(x-1)^2-1=0\end{array} \right.\) 
    ->  \(\left[ \begin{array}{l}x=1\\x=0\\x=2\end{array} \right.\) 
    Vậy x \in {1 ; 0 ; 2} 
    $\\$
    \text{b)}
    x – 5 – 1/3 = 3 . x/4 + 1/5
    -> x – 5 – 1/3 = {3x}/4 + 1/5
    -> x – {3x}/4 = 1/5 +1/3 +5
    -> {4x}/{4} – {3x}/4 = 83/15
    -> x/4 = 83/15
    -> x = 332/15
    Vậy x =332/15

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

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