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

Toán Lớp 8: Thực hiện phép tính b)(6x-5)²-18x(2x-4) c)(x+3)³-(x-2)(x²+2x+4) d)(x-1)³-(x+3)(x²-3x+9)

Toán Lớp 8: Thực hiện phép tính
b)(6x-5)²-18x(2x-4)
c)(x+3)³-(x-2)(x²+2x+4)
d)(x-1)³-(x+3)(x²-3x+9)

Comments ( 2 )

  1. b) (6x-5)^2-18x(2x-4)
    =(6x)^2-2·6x·5+5^2-18x·2x+18x·4
    =36x^2-60x+25-36x^2+72x
    =12x+25
    c) (x+3)^3-(x-2)(x²+2x+4)
    =x^3+3·x^2·3+3·x·3^2+3^3-(x^3-2^3)
    =x^3+9x^2+27x+27-x^3+8
    =9x^2+27x+35
    d) (x-1)^3-(x+3)(x²-3x+9)
    =x^3-3·x^2·1+3·x·1^2-1^3-(x^3+3^3)
    =x^3-3x^2+3x-1-x^3-27
    =-3x^2+3x-28
    Chúc bạn học tốt, cho mình câu trả lời hay nhất + 5* + cám ơn nha!!!

  2. b)=(6x)^2-2.6x.5+5^2-(36x^2-72x)
    =36x^2-60x+25-36x^2+72x
    =(36x^2-36x^2)+(-60x+72x)+25
    =12x+25
    c)=x^3+3.x^2.3+3.x.3^2+3^3-x^3+2^3
    =x^3+9x^2+27x+27-x^3+8
    =(x^3-x^3)+(27+8)+9x^2+27x
    =35+9x^2+27x
    d)=x^3-3.x^2.1+3.x.1^2-1^3-x^3-3^3
    =x^3-3x^2+3x-1-x^3-27
    =(x^3-x^3)+(-1-27)-3x^2+3x
    =-28-3x^2+3x

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

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