3 ( x mũ 4 + x mũ 2 + 1 ) – ( x mũ 2 +x+1) mũ 2

Question

3 ( x mũ 4 + x mũ 2 + 1 ) – ( x mũ 2 +x+1) mũ 2

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Sapo 4 years 2020-10-25T12:51:09+00:00 2 Answers 137 views 0

Answers ( )

  1. Vodka
    0
    2020-10-25T12:52:20+00:00
    Reply

    Áp dụng HĐT mở rộng: (a + b + c)² = a² + b² + c² + 2ab + 2bc + 2ac

    ——————–

    3(x^4 + x^2 + 1) – (x^2 + x + 1)^2

    = (3x^4 + 3x^2 + 3) – (x^4 + x^2 + 1 + 2x^3 + 2x^2 + 2x)

    = 3x^4 + 3x^2 + 1 – x^4 – x^2 – 1 – 2x^3 – 2x^2 – 2x

    = (3x^4 – x^4) + 2x^3 + (3x^2 – x^2 – 2x^2) – 2x + (1 – 1)

    = 2x^4 + 2x^3 – 2x

    @vietdorapan

  2. Ben
    0
    2020-10-25T12:52:52+00:00
    Reply

    $3.(x^4+x^2+1)-(x^2+x+1)^2_{}$

    $⇔3x^4+3x^2+3-(x^4+x^2+1+2x^3+2x^2+2x)_{}$

    $⇔3x^4+3x^2+3-x^4-x^2-1-2x^3-2x^2-2x_{}$

    $⇔2x^4-2x^3-2x+2_{}$

    $⇔2x^3.(x-1)-2.(x-1)_{}$

    $⇔(x-10).(2x^3-2)_{}$

    $⇔2.(x-1)(x^3-1)_{}$

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Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )