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

Toán Lớp 8: Rút gon A)(5-x)(x+2)-x(3x+1)+(2x)^2 B)(3x-1)^2-(x-3)(x+3)+(x+4)^2

Toán Lớp 8: Rút gon
A)(5-x)(x+2)-x(3x+1)+(2x)^2
B)(3x-1)^2-(x-3)(x+3)+(x+4)^2

Comments ( 2 )

  1. Giải đáp:
     
    Lời giải và giải thích chi tiết:
    a) (5-x)(x+2)-x(3x+1)+(2x)^2
    =(5x + 10 – x^2 – 2x)-3x^2 – x + 4x^2
    =-x^2 – 3x^2 + 4x^2 – 2x –  x + 5x +10
    =2x + 10
    =2(x+5)
    b)(3x-1)^2 – (x-3)(x+3) + (x+4)^2
    =((3x)^2 – 2.3x.1 + 1) – (x^2 +3x – 3x – 9) + (x^2 + 2.x.4 + 16)
    =9x^2 – 6x + 1 – x^2 – 3x + 3x + 9 + x ^2 + 8x + 16
    =9x^2 + 2x + 26

  2. A, (5-x)(x+2) – x(3x+1) + (2x)^2
    = 5x + 10 – x^2 – 2x – 3x^2 -x + 4x^2
    = (5x -2x -x) +10 + (-x^2 – 3x^2 + 4x^2 )
    = 2x + 10
    B, (3x-1)^2 – (x-3)(x+3) + (x+4)^2
    = 9x^2 – 6x + 1 – x^2 + 9 + x^2 + 8x + 16
    = (9x^2 – x^2 + x^2 ) + (-6x + 8x) + (1+9+16)
    = 9x^2 +2x+26
     

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

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