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

Toán Lớp 8: 1. 2x mũ 2 y – 6xy mũ 2 2. 3x (x-1) + 7x mũ 2 (x -1) 3.6x mũ 4 -9x mũ 3 4. 10x ( x -y ) -8y ( y -x) 5 . X mũ 3 + 6x mũ 2 y + 12xy mũ

Toán Lớp 8: 1. 2x mũ 2 y – 6xy mũ 2
2. 3x (x-1) + 7x mũ 2 (x -1)
3.6x mũ 4 -9x mũ 3
4. 10x ( x -y ) -8y ( y -x)
5 . X mũ 3 + 6x mũ 2 y + 12xy mũ 2 + 8y mũ 3
6 . X mũ 3 -64
7. 14 xy – x mũ 2 – 49
Giúp mình đi ạ mình đang cần gấp

Comments ( 1 )

  1. Giải đáp:
    $\begin{array}{l}
    1)2{x^2}y – 6x{y^2}\\
     = 2xy\left( {x – 3y} \right)\\
    2)3x\left( {x – 1} \right) + 7{x^2}\left( {x – 1} \right)\\
     = x\left( {x – 1} \right)\left( {3 + 7x} \right)\\
    3)6{x^4} – 9{x^3} = 3{x^3}\left( {2x – 3} \right)\\
    4)10x\left( {x – y} \right) – 8y\left( {y – x} \right)\\
     = 2\left( {x – y} \right)\left( {5x + 4y} \right)\\
    5){x^3} + 6{x^2}y + 12x{y^2} + 8{y^3}\\
     = {\left( {x + 2y} \right)^3}\\
    6){x^3} – 64\\
     = \left( {x – 4} \right)\left( {{x^2} + 4x + 16} \right)\\
    7)14xy – {x^2} – 49\\
     =  – \left( {{x^2} – 14xy + {7^2}} \right)\\
     =  – {\left( {x – 7} \right)^2}
    \end{array}$

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

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