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

Toán Lớp 8: TÍNH (3x^3-2x^2+x+2 ). (5x^2) b, (3x^2+5x-2). (2x^2-4x+3)

Toán Lớp 8: TÍNH
(3x^3-2x^2+x+2 ). (5x^2)
b, (3x^2+5x-2). (2x^2-4x+3)

Comments ( 2 )

  1. Giải đáp + Lời giải và giải thích chi tiết:
    a) (3x^3-2x^2+x+2) . (5x^2)
    = (3x^3.5x^2) + (-2x^2.5x^2) + (x.5x^2) + (2.5x^2)
    = 15x^5 – 10x^4 + 5x^3 + 10x^2
    b) (3x^2+5x-2) . (2x^2-4x+3)
    =(3x^2+5x-2).(2x^2)+(3x^2+5x-2).(-4x)+ (3x^2+5x-2) . 3
    = 6x^4 + 10x^3 – 4x^2 – 12x^3 – 20x^2 + 8x + 9x^2 + 15x – 6
    = 6x^4 – 2x^3 – 15x^2 + 23x – 6
     

  2. Giải đáp:
     (3x^3-2x^2+x+2).5x^2
    =3x^{3}.5x^2-2x^{2}.5x^2+x.5x^2+2.5x^2
    =15x^5-10x^4+5x^3+10x^2
    b) (3x^2+5x-2)(2x^2-4x+3)
    =3x^{2}.2x^2-3x^{2}.4x+3x^{2}.3+5x.2x^2-5x.4x+5x.3-2.2x^2+2.4x-2.3
    =6x^4-12x^3+9x^2+10x^3-20x^2+15x-4x^2+8x-6
    =6x^4-2x^3-15x^2+23x-6
     

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