Tìm x , biết : a) 2.(x+1)-4x=15 b) (x-1).(x+1)-x.(x+4) d) x mũ 2 – 6x = 9 Giúp tui zớii Vote 5 sao + ctlhn ạ

Question

Tìm x , biết :
a) 2.(x+1)-4x=15
b) (x-1).(x+1)-x.(x+4)
d) x mũ 2 – 6x = 9
Giúp tui zớii
Vote 5 sao + ctlhn ạ

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RI SƠ 5 years 2020-11-05T03:07:12+00:00 1 Answers 84 views 0

Answers ( )

  1. Bo
    0
    2020-11-05T03:08:34+00:00
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    a) $2(x+1)-4x=15$

    $↔2x+2-4x=15$

    $↔-2x=13$

    $↔x=-\dfrac{13}{2}$

    b) $(x-1)(x+1)-x(x+4)$

    $=x^2-1-x^2-4x$

    $=-1-4x$

    c) $x^2-6x=9$

    $↔x^2-6x+9-9=0$

    $↔(x-3)^2=9$

    $\begin{cases}x-3=3\\x-3=-3\end{cases}$

    $\begin{cases}x=6\\x=0\end{cases}$

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