Tính : a) 1/2x × (-4/3x) ; b) (-2/3) × (-5/4x^2 – 6x + 3/8) ; c) (2+x) × (-x^2 +3x -1) d) (-5x^4+15x^3-18x) : (-5x)

1 bình luận về “Tính : a) 1/2x × (-4/3x) ; b) (-2/3) × (-5/4x^2 – 6x + 3/8) ; c) (2+x) × (-x^2 +3x -1) d) (-5x^4+15x^3-18x) : (-5x)”

1. a) 1/2x * (-4/3x)

   = (1/2 * (-4)/3)*(x.x)

   = (-2)/3x^2

   ———–

   b) (-2/3) * (-5/4x^2 – 6x + 3/8)

   = 2/3 * 5/4x^2 + 2/3 * 6x – 2/3 * 3/8

   = 5/6x^2 + 4x – 1/4

   ———–

   c) (2+x) . (-x^2 + 3x – 1)

   = – 2 . x^2 + 2 . 3x – 2 . 1 – x. x^2 + x. 3x – x. 1

   = – 2x^2 + 6x – 2 – x^3 + 3x^2 – x

   = – x^3 + (-2x^2 + 3x^2) + (6x-x) – 2

   = – x^3 + x^2 + 5x – 2

   ———–

   d) (-5x^4 + 15x^3 – 18x) : (-5x)

   = 5x^4 : 5x – 15x^3 : 5x + 18x : 5x

   = x^3 – 3x^2 + 3,6

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