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

Toán Lớp 8: Tính: (x+4)(x-2)-(x-3)^2 Tìm x: 4x(x-2)-6+3x=0

Tháng Chín 3, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: Tính:
(x+4)(x-2)-(x-3)^2
Tìm x:
4x(x-2)-6+3x=0

Comments ( 2 )

  1. huenthanh97
    huenthanh97
    3 Tháng Chín, 2022 at 4:39 chiều
    Reply
    Tính:
    ( x + 4)( x – 2) – $(x – 3)^{2}$ 
    = $x^{2}$ – 2x + 4x – 8 – $x^{2}$ + 6x – 9
    = 8x – 17
    Tìm x:
    4x( x – 2) – 6+3x = 0
    <=>    4x( x – 2) – 3( x – 2 ) = 0
    <=> ( x – 2 ). (4x – 3) = 0
    <=>\(\left[ \begin{array}{l}x – 2 = 0\\4x – 3 = 0\end{array} \right.\)
    <=>\(\left[ \begin{array}{l}x=2\\x=\frac{3}{4}\end{array} \right.\)
    S = {2 ; $\frac{3}{4}$ }

  2. dongoclandiem
    dongoclandiem
    3 Tháng Chín, 2022 at 4:39 chiều
    Reply
    a) (x+4)(x-2)-(x-3)^2
    =x^2-2x+4x-8-x^2+6x-9
    =(x^2-x^2)+(4x-2x+6x)+(-9-8)
    =8x-17
    * (a-b)^2=a^2-2ab+b^2
    b) 4x(x-2)-6+3x=0
    ⇔4x(x-2)+(3x-6)=0
    ⇔4x(x-2)+3(x-2)=0
    ⇔(x-2)(4x+3)=0
    ⇔\(\left[ \begin{array}{l}x-2=0\\4x+3=0\end{array} \right.\) 
    ⇔\(\left[ \begin{array}{l}x=2\\x=-\dfrac{3}{4}\end{array} \right.\) 
    Vậy x=2 hoặc x=-3/4
     

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

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