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

Toán Lớp 8: 1) (x + 1)(x – 1) – (x – 2)(x + 3) 2) (3x – 1) + 2(3x – 1)(2x + 1) + (2x + 1)^2 3) (2x + 1)^2 + 2(4x 2 – 1) + (2x – 1)^2 4) (x^2 – 1)(

Home/ Toán Lớp 8: 1) (x + 1)(x – 1) – (x – 2)(x + 3) 2) (3x – 1) + 2(3x – 1)(2x + 1) + (2x + 1)^2 3) (2x + 1)^2 + 2(4x 2 – 1) + (2x – 1)^2 4) (x^2 – 1)(

Toán Lớp 8: 1) (x + 1)(x – 1) – (x – 2)(x + 3) 2) (3x – 1) + 2(3x – 1)(2x + 1) + (2x + 1)^2 3) (2x + 1)^2 + 2(4x 2 – 1) + (2x – 1)^2 4) (x^2 – 1)(

Tháng Mười Hai 7, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: 1) (x + 1)(x – 1) – (x – 2)(x + 3)
2) (3x – 1) + 2(3x – 1)(2x + 1) + (2x + 1)^2
3) (2x + 1)^2 + 2(4x 2 – 1) + (2x – 1)^2
4) (x^2 – 1)(x + 2) – (x – 2)(x^2 + 2x + 4)
help

Comments ( 2 )

  1. hothaibinh
    hothaibinh
    7 Tháng Mười Hai, 2022 at 4:42 chiều
    Reply
    1) (x + 1)(x – 1) – (x – 2)(x + 3)
    ⇔ x²-x+x-1-x²+3x+2x+6
    ⇔ 5x+5 
    2) (3x – 1) + 2(3x – 1)(2x + 1) + (2x + 1)^2
    ⇔ 3x-1 +2(6x²+3x−2x−1)+4x²+4x+1
    ⇔3x-1 +12x²+6x -4x -2 +4x²+4x +1 
    ⇔ 16x² + 9x -2 
    3) (2x + 1)² + 2(4x² – 1) + (2x – 1)² 
    ⇔ (2x+1)² + 2(2x-1)(2x+1) + (2x-1)² 
    ⇔ (2x+1+2x-1)² 
    ⇔ (4x)² 
    ⇔ 16x² 
    4) (x² – 1)(x + 2) – (x – 2)(x²+ 2x + 4)
    ⇔ x³ +2x² -x -2 -(x³ -2³) 
    ⇔ x³ +2x² -x -2 – x³ +8 
    ⇔ 2x² -x +6 
    Xin 5 sao và ctlhn nha ! 

  2. behocgioitoan
    behocgioitoan
    7 Tháng Mười Hai, 2022 at 4:41 chiều
    Reply
    Giải đáp: + Lời giải và giải thích chi tiết:
    $1) (x + 1)(x – 1) – (x – 2)(x + 3)$
    $= x² – 1 – (x² + 3x – 2x – 6)$
    $= x² – 1 – x² – x + 6$
    $= -x + 5$
    $2) (3x – 1)² + 2(3x-1)(2x + 1) +(2x + 1)²$
    $= (3x – 1 + 2x + 1)²$ ($ A² + 2AB + B² = (A+B)²$ )
    $= (5x)² = 25x²$
    $3) (2x + 1)² + 2(4x² – 1) + (2x-1)²$
    $= (2x + 1)² + 2[(2x)² – 1²] + (2x-1)²$
    $= (2x + 1)² + 2(2x-1)(2x + 1) + (2x-1)²$
    $= (2x + 1 + 2x – 1)² = (4x)² = 16x²$
    $4) (x² – 1)(x+2) – (x-2)(x² + 2x + 4)$
    $= (x³ + 2x² – x – 2) – (x³ – 8)$
    $= x³ + 2x² – x – 2 – x³ + 8$
    $= 2x² – x + 6$

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

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