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

Toán Lớp 8: Tìm x để a)2.(x-1)^2-3x^2=5-(x-3)^2 b) (2x-1)^4=(2x-1)^2 c) 3x^2+6x=-3 Cho hay nhất nếu nhanh

Tháng Sáu 19, 2022 Toán học 1 Comment 0 views

Toán Lớp 8: Tìm x để
a)2.(x-1)^2-3x^2=5-(x-3)^2
b) (2x-1)^4=(2x-1)^2
c) 3x^2+6x=-3
Cho hay nhất nếu nhanh

Comments ( 1 )

  1. hienthucthu97
    hienthucthu97
    19 Tháng Sáu, 2022 at 4:26 sáng
    Reply
    $a)2(x-1)^{2}-3x^{2}=5-(x-3)^2$ 
    $⇔2(x^{2}-2x+1)-3x^{2}=5-(x^2-6x+9)$ 
    $⇔2x^{2}-4x+2-3x^{2}=5-x^2+6x-9$ 
    $⇔-4x+2-x^{2}=-x^2+6x-4$ 
    $⇔-4x+2=-x^2+6x-4+x^2$ 
    $⇔-4x+2=6x-4$ 
    $⇔2+4=6x+4x$ 
    $⇔6=10x$
    $⇔x=\dfrac{5}{3}$
    $b)(2x-1)^{4}=(2x-1)^2$
    $⇔(2x-1)^{2}.(2x-1)^{2}=(2x-1)^2$
    $⇔(2x-1)^{2}=1$
    $⇔$\(\left[ \begin{array}{l}2x-1=1\\2x-1=-1\end{array} \right.\)
    $⇔$\(\left[ \begin{array}{l}x=1\\x=0\end{array} \right.\)
    $c)3x^{2}+6x=-3$
    $⇔3x^{2}+6x+3=0$
    $⇔3(x^{2}+2x+1)=0$
    $⇔x^{2}+2x+1=0$
    $⇔(x+1)^2=0$
    $⇔x+1=0$
    $⇔x=-1$

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

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