1,5(x+3)-4x(3+x)=0 2,4x(x-2004)-x+2004=0 3,x²+8x+16=0 4,4x²-12x=-9

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1. Đáp án:

    

   Giải thích các bước giải:

   `1) 5.(x + 3) – 4x.(3 + x) = 0.`

   `⇒ 5.(x + 3) – 4x.(x + 3) = 0.`

   `⇒ (5 – 4x).(x + 3) = 0.`

   `⇒` \(\left[ \begin{array}{l}5-4x=0.\\x+3=0.\end{array} \right.\)

   `⇒` \(\left[ \begin{array}{l}4x=5.\\x=-3.\end{array} \right.\)

   `⇒` \(\left[ \begin{array}{l}x=\dfrac{5}{4}.\\x=-3.\end{array} \right.\)

   Vậy `x=5/4` hoặc `x=-3.`

   `2) 4x.(x – 2004) – x + 2004 = 0.`

   `⇒ 4x.(x – 2004) – (x – 2004) = 0.`

   `⇒ (4x – 1).(x – 2004) = 0.`

   `⇒` \(\left[ \begin{array}{l}4x-1=0.\\x-2004=0.\end{array} \right.\)

   `⇒` \(\left[ \begin{array}{l}4x=1.\\x=2004.\end{array} \right.\)

   `⇒` \(\left[ \begin{array}{l}x=\dfrac{1}{4}.\\x=2004.\end{array} \right.\)

   Vậy `x = 1/4` hoặc `x = 2004.`

   `3) x^2 + 8x + 16 = 0.`

   `⇒ x^2 + 2.x.4 + 4^2 = 0.`

   `⇒ (x + 4)^2 = 0.`

   `⇒ x + 4 = 0.`

   `⇒ x = -4.`

   Vậy `x = -4.`

   `4) 4x^2 – 12x = -9.`

   `⇒ 4x^2 – 12x + 9 = 0.`

   `⇒ (2x)^2 – 2.2x.3 + 3^2 = 0.`

   `⇒ (2x – 3)^2 = 0.`

   `⇒ 2x – 3 = 0.`

   `⇒ 2x = 3.`

   `⇒ x = 3/2.`

   $\text{Vậy x = $\dfrac{3}{2}$.}$

   $\text{Cho mik xin câu trả lời hay nhất nha, kiếm chút cho nhóm.}$

   $\text{Mấy nay bận nên off hơi nhiều.}$

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2. Giải thích các bước giải:

    1, `5(x+3)-4x(3+x)=0`

   `=>(5-4x)(x+3)=0`

   `=>`\(\left[ \begin{array}{l}5-4x=0\\x+3=0\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=\dfrac54\\x=-3\end{array} \right.\)

    2, `4x(x-2004)-x+2004=0`

   `=>4x(x-2004)-(x-2004)=0`

   `=>(4x-1)(x-2004)=0`

   `=>`\(\left[ \begin{array}{l}4x-1=0\\x-2004=0\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=\dfrac14\\x=2004\end{array} \right.\)

    3, `x^2+8x+16=0`

   `=>(x+4)^2=0`

   `=>x+4=0`

   `=>x=-4`

    4, `4x^2-12x=-9`

   `=>4x^2-12x+9=0`

   `=>(2x-3)^2=0`

   `=>2x-3=0`

   `=>x=3/2`

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