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

Toán Lớp 8: 1.thực hiện phép tính A,x^3.(3x^2-2x+4) B,(x-3)(x^2+3x-5)

Toán Lớp 8: 1.thực hiện phép tính
A,x^3.(3x^2-2x+4)
B,(x-3)(x^2+3x-5)

Comments ( 2 )

  1. a) x³.(3x² – 2x + 4)
    = x³.3x² – x³.2x + x³.4
    = $3x^{5}$ – $2x^{4}$ + 4x³
    b) (x – 3)(x² + 3x – 5)
    = (x.x² + 3x.x – x.5) – (3.x² + 3.3x – 3.5)
    = x³ + 3x² – 5x – 3x² – 9x + 15
    = x³ – 14x + 15
    $\textit{Shiii}$
     

  2. Answer
    a, x^{3} . (3x^{2} – 2x + 4)
    = x^{3} . 3x^{2} – x^{3} . 2x + x^{3} . 4
    = 3x^{5} – 2x^{4} + 4x^{3}
    _____________________
    b, (x – 3) . (x^{2} + 3x – 5)
    = x . x^{2} + x . 3x – x . 5 – 3 . x^{2} – 3 . 3x + 3 . 5
    = x^{3} + 3x^{2} – 5x – 3x^{2} – 9x + 15
    = x^{3} + (3x^{2} – 3x^{2}) + (-5x – 9x) + 15
    = x^{3} – 14x + 15

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

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