giúp mk chuyên gia toán ơi

Question

giúp mk chuyên gia toán ơi
giup-mk-chuyen-gia-toan-oi

in progress 0
Cherry 4 years 2020-10-21T07:48:18+00:00 2 Answers 76 views 0

Answers ( )

  1. Vodka
    0
    2020-10-21T07:49:33+00:00
    Reply

    8a) $x^2 + 2x – 24 = 0$

    $\Leftrightarrow (x+6)(x -4) = 0$

    $\Leftrightarrow \left[\begin{array}{l}x = -6\\x = 4\end{array}\right.$

    b) $2x^2 + 5x – 3 = 0$

    $\Leftrightarrow (x +1)\left(x -\dfrac{3}{2}\right) = 0$

    $\Leftrightarrow \left[\begin{array}{l}x = -1\\x = \dfrac{3}{2}\end{array}\right.$

    c) $3x^2 = -5x + 2$

    $\Leftrightarrow (x +1)\left(x -\dfrac{2}{3}\right) = 0$

    $\Leftrightarrow \left[\begin{array}{l}x = -1\\x = \dfrac{2}{3}\end{array}\right.$

    9) $(x^2 +3x – 10)(x^2 – 5x – 6)$

    $= (x + 5)(x -2)(x +1)(x – 6)$

    $= [(x + 5)(x – 6)][(x -2)(x +1)]$

    $= (x^2 – x – 30)(x^2 – x -2)$

  2. Maris
    0
    2020-10-21T07:49:44+00:00
    Reply

    Đáp án:

     

    Giải thích các bước giải:

     a) `x^2+2x-24=0`

    `⇔ x^2-4x+6x-24=0`

    `⇔ x(x-4)+6(x-4)=0`

    `⇔ (x+6)(x-4)=0`

    `⇔` \(\left[ \begin{array}{l}x+6=0\\x-4=0\end{array} \right.\) 

    `⇔` \(\left[ \begin{array}{l}x=-6\\x=4\end{array} \right.\) 

    Vậy `S={-6;4}`

    b) `2x^2+5x-3=0`

    `⇔ 2x^2+6x-x-3=0`

    `⇔ (2x-1)(x+3)=0`

    `⇔` \(\left[ \begin{array}{l}x=\dfrac{1}{2}\\x=-3\end{array} \right.\) 

    Vậy `S={1/2;-3}`

    c) `3x^2=-5x+2`

    `⇔ 3x^2+5x-2=0`

    `⇔ (3x-1)(x+2)=0`

    `⇔` \(\left[ \begin{array}{l}x=\dfrac{1}{3}\\x=-2\end{array} \right.\) 

    Vậy `S={1/3;-2}`

    9/

    `(x^2+3x-10)(x^2-5x-6)=(x^2-x-2)(x^2-x-30)`

    `VT=x^4-2x^3-31x^2+32x+60`

    `VP=x^4-2x^3-31x^2+32x+60`

    `⇒ VT=VP` 

    Vậy đẳng thức đã được chứng minh

Leave an answer

Browse

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