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

Toán Lớp 8: 5x(1/5x-2)+3(6-1/3x^2)=12 3x(4/3x+1-4x(x-2)=10 (x+3)(x^2-3x+9)-x(5+x^2)=52 4x(5-x)+(x-1)=4

Tháng Bảy 26, 2022 Toán học 1 Comment 0 views

Toán Lớp 8: 5x(1/5x-2)+3(6-1/3x^2)=12
3x(4/3x+1-4x(x-2)=10
(x+3)(x^2-3x+9)-x(5+x^2)=52
4x(5-x)+(x-1)=4

Comments ( 1 )

  1. thanhbinh2k5
    thanhbinh2k5
    26 Tháng Bảy, 2022 at 10:36 sáng
    Reply
    Giải đáp:
    $a. x = \frac{3}{5}$
    $b. x = \frac{10}{11}$
    $c. x = – 5$
    $d.$ \(\left[ \begin{array}{l}x=5\\x=\frac{1}{4}\end{array} \right.\) 
    Lời giải và giải thích chi tiết:
    $a. 5x( \frac{1}{5}x – 2 ) + 3( 6 – \frac{1}{3}x^{2} ) = 12$
    ⇔ $x^{2} – 10x + 18 – x^{2} = 12$
    ⇔ $- 10x + 18 = 12$
    ⇔ $10x = 6$
    ⇔ $x = \frac{3}{5}$
    $b. 3x( \frac{4}{3}x + 1 ) – 4x( x – 2 ) = 10$
    ⇔ $4x^{2} + 3x – 4x^{2} + 8x = 10$
    ⇔ $11x = 10$
    ⇔ $x = \frac{10}{11}$
    $c. ( x + 3 )( x^{2} – 3x + 9 ) – x( 5 + x^{2} ) = 52$
    ⇔ $x^{3} + 3^{3} – 5x – x^{3} = 52$
    ⇔ $27 – 5x = 52$
    ⇔ $5x = – 25$
    ⇔ $x = – 5$
    $d. 4x( 5 – x ) + ( x – 1 ) = 4$
    ⇔ $20x – 4x^{2} + x – 1 = 4$
    ⇔ $- 4x^{2} + 21x – 1 = 4$
    ⇔ $4x^{2} – 21x + 5 = 0$
    ⇔ $( 4x^{2} – 20x ) – ( x – 5 ) = 0$
    ⇔ $4x( x – 5 ) – ( x – 5 ) = 0$
    ⇔ $( x – 5 )( 4x – 1 ) = 0$
    ⇔ \(\left[ \begin{array}{l}x=5\\x=\frac{1}{4}\end{array} \right.\) 

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

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