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

Toán Lớp 8: 1) (x + 2)(x2 – 2x + 4) – (15 + 2×3) 2) (3x – 2y)(9×2 + 6xy + 4y2) – (5×3 – 10y3) 3) (x2 + 2xy – 3).(-xy) 4) x2y(2×2 – xy2 – 1)

Home/ Toán Lớp 8: 1) (x + 2)(x2 – 2x + 4) – (15 + 2×3) 2) (3x – 2y)(9×2 + 6xy + 4y2) – (5×3 – 10y3) 3) (x2 + 2xy – 3).(-xy) 4) x2y(2×2 – xy2 – 1)

Toán Lớp 8: 1) (x + 2)(x2 – 2x + 4) – (15 + 2×3) 2) (3x – 2y)(9×2 + 6xy + 4y2) – (5×3 – 10y3) 3) (x2 + 2xy – 3).(-xy) 4) x2y(2×2 – xy2 – 1)

Tháng Một 19, 2023 Toán học 2 Comments 0 views

Toán Lớp 8: 1) (x + 2)(x2 – 2x + 4) – (15 + 2×3)
2) (3x – 2y)(9×2 + 6xy + 4y2) – (5×3 – 10y3)
3) (x2 + 2xy – 3).(-xy)
4) x2y(2×2 – xy2 – 1)
5) (x – 7)(x – 5)
6) (x – 1)(x + 1)( x + 2)
7) (x + 3)(x2 – 3x + 9) – (54 + x3)

Comments ( 2 )

  1. tuanh
    tuanh
    19 Tháng Một, 2023 at 6:54 chiều
    Reply
    1) $(x+2)(x^2-2x+4)-(15+2x^3)$
    $=x^3+8-15-2x^3$
    $=-x^3-7$
    2) $(3x-2y)(9x^2+6xy+4y^2)-(5x^3-10y^3)$
    $=27x^3-8y^3-5x^3+10y^3$
    $=22x^3+2y^3$
    3) $(x^2+2xy-3)(-xy)$
    $=x^2.(-xy)+2xy.(-xy)-3.(-xy)$
    $=-x^3y-2x^2y^2+3xy$
    4) $x^2y(2x^2-xy^2-1)$
    $=x^2y.2x^2-x^2y.xy^2-x^2y.1$
    $=2x^4y-x^3y^3-x^2y$
    5) $(x-7)(x-5)$
    $=x.x-x.5-7.x-7.(-5)$
    $=x^2-5x-7x+35$
    $=x^2-12x+35$
    6) $(x-1)(x+1)(x+2)$
    $=(x^2-1)(x+2)$
    $=x^2.x+x^2.2-1.x-1.2$
    $=x^3+2x^2-x-2$
    7) $(x+3)(x^2-3x+9)-(54+x^3)$
    $=x^3+27-54-x^3$
    $=-27$

  2. maianhtuanh
    maianhtuanh
    19 Tháng Một, 2023 at 6:53 chiều
    Reply
    1)(x+2)(x²-2x+4)-(15+2x³)
    =(x+2)(x²-x.2+2²)-(15+2x³)
    =x³+2³-15-2x³
    =x³+8-15-2x³
    =(x³-2x³)+(8-15)
    =-x³-7
    2)(3x-2y)(9x²+6xy+4y²)-(5x³-10y³)
    =(3x-2y)[(3x)²+3x.2y+(2y)²]-5x³+10y³
    =(3x)³-(2y)³-5x³+10y³
    =27x³-8y³-5x³+10y³
    =(27x³-5x³)+(-8y³+10y³)
    =22x³+2y³
    3)(x²+2xy-3).(-xy)
    =-x².xy-2xy.xy-3.(-xy)
    =-x³y-2x²y²+3xy
    4)x²y(2x²-xy²-1)
    =x²y.2x²-x²y.xy²-x²y.1
    =2x^4y-x³y³-x²y
    5)(x-7)(x-5)
    =x(x-5)-7(x-5)
    =x²-5x-7x+35
    =x²-12x+35
    6)(x-1)(x+1)(x+2)
    =(x²-1)(x+2)
    =x²(x+2)-1(x+2)
    =x³+2x²-x-2
    7)(x+3)(x²-3x+9)-(54+x³)
    =(x+3)(x²-x.3+3²)-54-x³
    =x³+3³-54-x³
    =x³+27-54-x³
    =(x³-x³)+(27-54)
    =-27
     

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

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