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

Toán Lớp 8: Bài 1: Rút gọn A = (3x – 1) ² + 2(3x -1) (2x+1) + (2x +1) ² B = (2x +3) (4x ² – 6x + 9) + 8(1 – x) (1 +x +x ²)

Toán Lớp 8: Bài 1: Rút gọn
A = (3x – 1) ² + 2(3x -1) (2x+1) + (2x +1) ²
B = (2x +3) (4x ² – 6x + 9) + 8(1 – x) (1 +x +x ²)

Comments ( 2 )

  1. A=(3x-1)^2+2(3x-1)(2x+1)+(2x+1)^2
    =[(3x-1)+(2x+1)]^2
    =(3x-1+2x+1)^2
    =(5x)^2
    =25x^2
    Vậy A=25x^2
    B=(2x+3)(4x^2-6x+9)+8(1-x)(1+x+x^2)
    =(2x+3)[(2x)^2-2x.3+3^2]+8(1-x)[1^2+1.x+x^2]
    =(2x)^3+3^3+8(1^3-x^3)
    =8x^3+27+8-8x^3
    =35
    Vậy B=35.

  2. Giải đáp:
    A=25x^2
    B=35
    Lời giải và giải thích chi tiết:
     A=(3x-1)^2+2(3x-1)(2x+1)+(2x+1)^2
    =[(3x-1)+(2x+1)]^2
    =(3x-1+2x+1)^2
    =(5x)^2
    =25x^2
    Vậy A=25x^2
    B=(2x+3)(4x^2-6x+9)+8(1-x)(1+x+x^2)
    =(2x+3)[(2x)^2-2x.3+3^2]+8(1-x)(1^2+1.x+x^2)
    =(2x)^3+3^3+8(1^3-x^3)
    =8x^3+27+8(1-x^3)
    =8x^3+27+8-8x^3
    =27+8
    =35
    Vậy B=35

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