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\(13,7.\left(-2,56\right)+46,31\div0,5-\left[86,3.2,56+53,69\div\left(-0,5\right)\right]\)
\(=\)\(-35,072+92,62-\left[220,928-107,38\right]\)
\(=\)\(57,548-220,928+107,38\)
\(=\)\(-163,38+107,38\)
\(=\)\(-56\)
3x2+2y2=7xy3x2+2y2=7xy
⇔3x2−7xy+2y2=0⇔3x2−7xy+2y2=0
⇔3x2−6xy−xy+2y2=0⇔3x2−6xy−xy+2y2=0
⇔3x(x−2y)−y(x−2y)=0⇔3x(x−2y)−y(x−2y)=0
⇔(3x−y)(x−2y)=0⇔(3x−y)(x−2y)=0
⇔[3x−y=0x−2y=0⇔[3x−y=0x−2y=0 ⇔[3x=yx=2y⇔[3x=yx=2y
+) TH1 : y=3xy=3x
⇔A=3x+y7y−x+6x−9y2x+y⇔A=3x+y7y−x+6x−9y2x+y
=3x+3x7.3x−x+6x−9.3x2x+3x=3x+3x7.3x−x+6x−9.3x2x+3x
=9x20x+−21x5x=9x20x+−21x5x
=−154=−154
+) TH2 : x=2yx=2y
⇔A=3x+y7y−x+6x−9y2x+y⇔A=3x+y7y−x+6x−9y2x+y
=3.2y+y7y−2y+6.2y−9y2.2y+y=3.2y+y7y−2y+6.2y−9y2.2y+y
=7y5y+3y5y=7y5y+3y5y
=2=2
Vậy...
211.\(\frac{9^2}{3^5}\).162
=211.\(\frac{\left(3^2\right)^2}{3^5}\).(24)2
=211.\(\frac{3^4}{3^5}\).28
=219.\(\frac{1}{3}\)
=\(\frac{2^{19}}{3}\)
đáp số : x = 2,4
giải thích các bước giải
\(\frac{x^2}{6}\)\(=\frac{24}{25}\)
Áp dụng tính chất hai phân số bằng nhau thì tích chéo của chúng bằng nhau
ta có : \(x^2\)\(.25=6.24\)
\(x^2\)\(.25=144\)
\(x^2\)\(=144:25=\frac{144}{25}\)\(=5,76\)
\(x^2\)\(=5,76=2,4^2\)
\(--->x=2,4\)
\(\frac{x^2}{6}=\frac{24}{25}\)
\(\Rightarrow x^2=\frac{24}{25}.6=\frac{144}{25}\)
\(\Rightarrow\orbr{\begin{cases}x^2=12^2\\x^2=\left(-12\right)^2\end{cases}}\Rightarrow\orbr{\begin{cases}x=12\\x=-12\end{cases}}\)
\(\left(\frac{3}{4}\right)^{2.x}:\left(\frac{2}{5}\right)^{10}=\left(\frac{15}{8}\right)^{10}\)
\(\left(\frac{3}{4}\right)^{2.x}=\left(\frac{15}{8}\right)^{10}.\left(\frac{2}{5}\right)^{10}\)
\(\left(\frac{3}{4}\right)^{2.x}=\left(\frac{15}{8}.\frac{2}{5}\right)^{10}\)
\(\left(\frac{3}{4}\right)^{2.x}=\left(\frac{3}{4}\right)^{10}\)
\(\Rightarrow2.x=10\Rightarrow x=5\)
\(\left(\frac{3}{4}\right)^{2x}\div\left(\frac{2}{5}\right)^{10}=\left(\frac{15}{8}\right)^{10}\)
\(\left(\frac{3}{4}\right)^{2x}=\left(\frac{15}{8}\right)^{10}\times\left(\frac{2}{5}\right)^{10}\)
\(\left(\frac{3}{4}\right)^{2x}=\left(\frac{15}{8}\times\frac{2}{5}\right)^{10}\)
\(\left(\frac{3}{4}\right)^{2x}=\left(\frac{3}{4}\right)^{10}\)
\(\Rightarrow\)\(2x=10\)
\(\Rightarrow\)\(x=5\)