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

Toán Lớp 8: ($x^{2}$ -5)(x+3)+(x+4)(x-x$x^{2}$ )

Toán Lớp 8: ($x^{2}$ -5)(x+3)+(x+4)(x-x$x^{2}$ )

Comments ( 2 )

  1. Giải đáp+Lời giải và giải thích chi tiết:
    (x^2-5)(x+3)+(x+4)(x-x^2)
    =x^3+3x^2-5x-15+x^2-x^3+4x-4x^2
    =(x^3-x^3)+(3x^2-4x^2+x^2)+(4x-5x)-15
    =-x-15 

  2. $\\$
    (x^2 – 5)(x+3)
    =x^2 (x+3)-5(x+3)
    = x^3 +3x^2 – 5x-15
    (x+4)(x -x^2)
    = x(x-x^2)+4(x-x^2)
    =x^2 – x^3 +4x – 4x^2
    = -x^3 + (x^2 – 4x^2)+4x
    =-x^3 -3x^2+4x
    (x^2 -5)(x+3)+(x+4)(x-x^2)
    = (x^3 +3x^2 – 5x-15)+(-x^3 -3x^2+4x)
    = x^3 +3x^2 -5x-15 -x^3 – 3x^2 + 4x
    = (x^3 -x^3)+(3x^2 – 3x^2)+(-5x+4x)-15
    =-x-15
     

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

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