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

Toán Lớp 8: a) 3x( x^2 – 5x + 3 ) + ( x+ 1).(x+2) b) ( x + 2 )^2 + ( x -3 )^2 – ( x- 1). ( x + 1) Khai triển

Toán Lớp 8: a) 3x( x^2 – 5x + 3 ) + ( x+ 1).(x+2)
b) ( x + 2 )^2 + ( x -3 )^2 – ( x- 1). ( x + 1)
Khai triển

Comments ( 2 )

  1. a)3x(x^2-5x+3)+(x+1)(x+2)
    =3x.x^2-3x.5x+3x.3+x.x+x.2+1.x+1.2
    =3x^3-15x^2+9x+x^2+2x+x+2
    =3x^3-15x^2+x^2+9x+2x+x+2
    =3x^3-14x^2+12x+2
    b)(x+2)^2+(x-3)^2-(x-1)(x+1)
    =(x+2)^2+(x-3)^2-(x.x+x.1-1.x-1.1)
    =(x^2+2.2x+2^2)+(x^2-2.x.3+3^2)-(x^2+x-x-1)
    =x^2+4x+4+x^2-6x+9-x^2-x+x+1
    =x^2+4x+4+x^2-6x+9-x^2+1
    =x^2-2x+14
     

  2. Giải đáp + Lời giải và giải thích chi tiết:
    #$hyn$
    $ a)3x(x^2-5x+3)+(x+1)(x+2)$ 
    $=3x^3-15x^2+9x+(x^2+2x+x+2)$
    $=3x^3-14x^2+12x+2$
    $b)(x+2)^2+(x-3)^2-(x-1)(x+1)$
    $=(x^2+4x+4)+(x^2-6x+9)-(x^2+x-x-1)$
    $=x^2+4x+4+x^2-6x+9-x^2+1$
    $=x^2-2x+14$

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

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