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

Toán Lớp 8: c,(x-2) ×(x ²-5x+1)-x(x ²+11) d,x(1-3x)(4-3x)-(x-4)(3x+5)

Toán Lớp 8: c,(x-2) ×(x ²-5x+1)-x(x ²+11) d,x(1-3x)(4-3x)-(x-4)(3x+5)

Comments ( 2 )

  1. c) (x-2)(x^2-5x+1)-x(x^2+11)
    =x^3-5x^2+x-2x^2+10x-2-x^3-11x
    =-7x^2-2
    d) x(1-3x)(4-3x)-(x-4)(3x+5)
    =x(4-3x-12x+9x^2)-(3x^2+5x-12x-20)
    =4x-15x^2+9x^3-3x^2+7x+20
    =9x^3-18x^2+11x+20

  2. Giải đáp + Lời giải và giải thích chi tiết:
    c)
    (x-2)xx(x^2-5x+1)-x(x^2+11)
    =x xx(x^2-5x+1)-2 xx(x^2-5x+1)-x^3-11x
    =x^3-5x^2+x-2x^2+10x-2-x^3-11x
    =(x^3-x^3) -(5x^2+2x^2)+(x+10x-11x)-2
    =-7x^2-2
    d)
    x(1-3x)(4-3x)-(x-4)(3x+5)
    =x(4-3x-12x+9x^2)-(3x^2+5x-12x-20)
    =x(9x^2-15x+4)-(3x^2-7x-20)
    =9x^3-15x^2+4x-3x^2+7x+20
    =9x^3-(15x^2+3x^2)+(4x+7x)+20
    =9x^3-18x^2+11x+20

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