Tìm x biết \(\left(3x-2\right)^4=\left(3x-2\right)^6\)
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dễ mà
bn chia 2 trường hợp
TH1 : 3x - 4 = 6
TH2 : x + 2 = 6
Vậy ....
bn tự tính nha .. bn hỉu hăm ??
a/ \(x=\dfrac{-5}{12}\)
b/ \(x\approx-1,9526\)
c/ \(x=\dfrac{21-i\sqrt{199}}{10}\)
d/ \(x=\dfrac{-20}{13}\)
\(\left(x-3\right)^3-\left(x-3\right)\left(x^2+3x+9\right)+6\left(x+1\right)^2+3x^2=-33\)
<=> \(x^3-9x^2+27x-27\) \(-\left(x^3-3^3\right)+6\left(x^2+2x+1\right)+3x^2=-33\)
<=> \(x^3-9x^2+27x-27-x^3+27+6x^2+12x+6+3x^2=-33\)
<=> \(-6x^2+39x+6=-33\)
<=> \(6x^2-39x-6=33\)
<=> \(6x^2-39x-39=0\)
<=> \(6\left(x^2-\frac{39}{6}x-\frac{39}{6}\right)=0\)
<=> \(x^2-2.x.\frac{39}{12}+\frac{1521}{144}-\frac{273}{16}=0\)
<=> \(\left(x-\frac{39}{12}\right)^2-\frac{273}{16}=0\)
<=> \(\left(x-\frac{39}{12}-\frac{\sqrt{273}}{4}\right)\left(x-\frac{39}{12}+\frac{\sqrt{273}}{4}\right)=0\)
<=> \(\left(x-\frac{13+\sqrt{273}}{4}\right).\left(x-\frac{13-\sqrt{273}}{4}\right)=0\)
<=> \(x=\frac{13+\sqrt{273}}{4}\) ( h ) \(x=\frac{13-\sqrt{273}}{4}\)
học tốt
Ta có: \(\left(3x-2\right)^4=\left(3x-2\right)^6\)
\(\Leftrightarrow\left(3x-2\right)^4-\left(3x-2\right)^6=0\)
\(\Leftrightarrow\left(3x-2\right)^4\left[1-\left(3x-2\right)^2\right]=0\)
+ \(\left(3x-2\right)^4=0\)\(\Leftrightarrow\)\(3x-2=0\)\(\Leftrightarrow\)\(x=\frac{2}{3}\)
+ \(1-\left(3x-2\right)^2=0\)\(\Leftrightarrow\)\(\left(3x-2\right)^2=1\)
\(\Leftrightarrow\)\(3x-2=\pm1\)
\(\Leftrightarrow\)\(\orbr{\begin{cases}x=1\\x=\frac{1}{3}\end{cases}}\)
Vậy \(x=\frac{2}{3}\)hoặc \(x=\frac{1}{3}\)hoặc \(x=1\)