Tìm x: $4x(2x^{2}$$-1)+27=$ $(4x^{2}$$+6x+9)(2x+3)$

Question

Tìm x:
$4x(2x^{2}$$-1)+27=$ $(4x^{2}$$+6x+9)(2x+3)$

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Calantha 5 years 2020-10-29T00:50:46+00:00 2 Answers 88 views 0

Answers ( )

  1. quangkhai
    0
    2020-10-29T00:52:20+00:00
    Reply

    `4x(2x^2-1)+27=(4x^2+6x+9)(2x+3)`

    `=>8x^3-4x+27=8x^3+12x^2+12x^2+18x+18x+27`

    `=>(8x^3-8x^3)+(27-27)=24x^2+40x`

    `=>x(24x+40)=0`

    `=>`\(\left[ \begin{array}{l}x=0\\24x=40\end{array} \right.\) 

    `=>`\(\left[ \begin{array}{l}x=0\\x=5/3\end{array} \right.\) 

     

  2. dangkhoa
    0
    2020-10-29T00:52:28+00:00
    Reply

    Đáp án:

     

    Giải thích các bước giải:

     4x(2x²-1)+27=(4x²+6x+9)(2x+3)

    8x³-4x+27=8x³+12x²+12x²+18x+18x+27

    (8x³-8x³)+(-12x²-12x²)+(-4x-18x-18x)=27-27

    -24x²-40x=0

    -(24x²+40x)=0

    x(24x+40)=0

    =>x=0

         hoặc 24x +40=0

    => x=5/3

    => x∈{0;5/3}

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