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

Toán Lớp 8: 1)-$\frac{1}{2}$ $x^{2}$ (3$x^{2}$ -7x +5) 2)(x+3)($x^{2}$ +3x-5) 3)($x^{2}$ -2xy+$y^{2}$).(x-y) làm đc câu nào thì lm

Toán Lớp 8: 1)-$\frac{1}{2}$ $x^{2}$ (3$x^{2}$ -7x +5)
2)(x+3)($x^{2}$ +3x-5)
3)($x^{2}$ -2xy+$y^{2}$).(x-y)
làm đc câu nào thì lm

Comments ( 2 )

  1. $@Shu$
    1) – 1/2 x^2 (3x^2 – 7x + 5)
    = – 3/2 x^4 – 7/2 x^3 – 5/2 x^2
    2) (x+3)(x^2 + 3x – 5)
    = x^3 + 3x^2 – 5x + 3x^2 + 9x – 15
    = x^3 + 6x^2 + 4x – 15
    3)(x^2 – 2xy + y^2).(x-y)
    = (x-y)^2 .(x-y)
    = (x-y)^3
    = x^3 – 3x^2y + 3xy^2 – y^3

  2. Giải đáp+Lời giải và giải thích chi tiết:
     1) -1/2x².(3x²-7x+5)
    = -1/2x².3x²+1/2x².7x-1/2x².5
    =-3/2x^4+7/2x³-5/2x²
    2) (x+3).(x²+3x-5)
    = x.(x²+3x-5)+3.(x²+3x-5)
    = x³+3x²-5x+3x²+9x-15
    = x³+6x²+4x-15
    3) (x²-2xy+y²).(x-y)
    = (x²-2.x.y+y²).(x-y)
    =(x-y)².(x-y)
    = (x-y)³
    = x³-3x²y+3xy²-y³
    CHÚC BN HC TỐT!!!
    @anhnguyenff

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