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

Toán Lớp 8: a) (x – 2) ² – (x + 3) ² + (x + 4) (x – 4) b) ( x – 1) ³ – x (x – 2) ² + x – 1 làm giúp mik nhé

Tháng Chín 17, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: a) (x – 2) ² – (x + 3) ² + (x + 4) (x – 4) b) ( x – 1) ³ – x (x – 2) ² + x – 1 làm giúp mik nhé

Comments ( 2 )

  1. tonhu12
    tonhu12
    17 Tháng Chín, 2022 at 10:27 sáng
    Reply
    Giải đáp:
     a, (x – 2)^2 – (x + 3)^2 + (x + 4)(x- 4)
    = x^2 – 2.x.2 + 2^2 – (x^2 + 2.x.3 + 3^2) + x^2 – 4^2
    = x^2 – 4x + 4 – x^2 – 6x – 9 + x^2 – 16
    = (x^2 – x^2 + x^2) + (-4x – 6x) + (4 – 9 – 16)
    = x^2 – 10x -21
    b, (x – 1)^3 – x(x – 2)^2 + x – 1
    = x^3 – 3.x^2 .1 + 3.x.1^2 – 1^3 – x(x^2 – 2.x.2 + 2^2) + x – 1
    = x^3 – 3x^2 + 3x – 1 –  x(x^2 – 4x + 4) + x – 1
    = x^3 – 3x^2 + 3x – 1 –  x^3 + 4x^2 – 4x + x – 1
    = (x^3 – x^3) + (4x^2 – 3x^2)  + (-4x + x + 3x) + (-1 – 1)
    = x^2 – 2

  2. minhtuquynh
    minhtuquynh
    17 Tháng Chín, 2022 at 10:26 sáng
    Reply
    Giải đáp:
    a) (x – 2) ² – (x + 3) ² + (x + 4) (x – 4)
    = x^2 + 4x+ 4 – x^2 – 6x – 9 + x^2 – 16
    = x^2 -2x – 21
    $\\$
    b, ( x – 1)  ³   –  x (x – 2) ² + x – 1
    =x^3-3x^2+3x-1 – x( x^2 – 4x + 4) + x -1
    = x^3 – 3x^2 + 3x – 1 – x^3 + 4x^2 – 4x + x -1
    = x^2 -2

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

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