Question

30-2(3x-1) mũ 2 =30-12 .giúp mình với

Answer 1

    \(30-2\left(3x-1\right)^2=30-12\)
\(\Leftrightarrow2\left(3x-1\right)^2=30-\left(30-12\right)=12\)
\(\Leftrightarrow\left(3x-1\right)^2=12:2=6\)
\(\Leftrightarrow\sqrt{\left(3x-1\right)^2}=\sqrt{6}\)
TH1:
\(\Leftrightarrow3x-1=\sqrt{6}\)
\(\Leftrightarrow3x=\sqrt{6}+1\)
\(\Leftrightarrow x=\dfrac{\sqrt{6}+1}{3}\)
TH2:
\(\Leftrightarrow3x-1=-\sqrt{6}\)
\(\Leftrightarrow3x=\left(-\sqrt{6}\right)+1\)
\(\Leftrightarrow x=\dfrac{\left(-\sqrt{6}\right)+1}{3}\)
Vậy \(x\in\left\{\dfrac{\sqrt{6}+1}{3};\dfrac{\left(-\sqrt{6}+1\right)}{3}\right\}\)


(đề cứ sai sai kiểu gì í)

\(\#PeaGea\)