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

Toán Lớp 8: (x+3)*(x-10)=1-x*(x-9) mn giúp em vs

Home/ Toán Lớp 8: (x+3)*(x-10)=1-x*(x-9) mn giúp em vs

Toán Lớp 8: (x+3)*(x-10)=1-x*(x-9) mn giúp em vs

Tháng Mười Hai 12, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: (x+3)*(x-10)=1-x*(x-9) mn giúp em vs

Comments ( 2 )

  1. buithaianh98
    buithaianh98
    12 Tháng Mười Hai, 2022 at 9:09 chiều
    Reply
    \qquad (x+3)(x-10)=1-x(x-9)
    <=> x^2-10x+3x-30=1-x^2+9x
    <=> x^2-7x-30=-x^2+9x+1
    <=> x^2-7x-30+x^2-9x-1=0
    <=> 2x^2-16x-31=0
    <=> x^2-8x-31/2=0
    <=> x^2-8x+16=63/2
    <=> (x-4)^2=63/2
    <=>\(\left[ \begin{array}{l}x-4=\dfrac{3\sqrt{14}}{2}\\x-4=\dfrac{-3\sqrt{14}}{2}\end{array} \right.\)
    <=>\(\left[ \begin{array}{l}x=\dfrac{8+3\sqrt{14}}{2}\\x=\dfrac{8-3\sqrt{14}}{2}\end{array} \right.\)
    Vậy S={(8+-3\sqrt{14})/2}

  2. cobexinhdep
    cobexinhdep
    12 Tháng Mười Hai, 2022 at 9:09 chiều
    Reply
    ~rai~
    \((x+3)(x-10)=1-x(x-9)\\\Leftrightarrow x^2-10x+3x-30=1-x^2+9x\\\Leftrightarrow x^2-10x+3x-30-1+x^2-9x=0\\\Leftrightarrow 2x^2-16x-31=0\\\Leftrightarrow (2x^2-16x+32)-63=0\\\Leftrightarrow 2(x^2-8x+16)=63\\\Leftrightarrow (x-4)^2=\dfrac{63}{2}\\\Leftrightarrow \left[\begin{array}{I}x-4=\dfrac{3\sqrt{14}}{2}\\x-4=-\dfrac{3\sqrt{14}}{2}\end{array}\right.\\\Leftrightarrow \left[\begin{array}{I}x=\dfrac{8+3\sqrt{14}}{2}\\x=\dfrac{8-3\sqrt{14}}{2}.\end{array}\right.\\\text{Vậy x=}\dfrac{8\pm3\sqrt{14}}{2}.\)
     

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

Thúy Mai

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