270*20+58*270+28*270=270*/20+58+28\=270*100=270 

ĐKXĐ:\(x\ne0,x\ne-12\)

\(\dfrac{270}{x}-\dfrac{270}{x+12}=\dfrac{7}{10}\\ \Leftrightarrow270\left(\dfrac{1}{x}-\dfrac{1}{x+12}\right)=\dfrac{7}{10}\\ \Leftrightarrow\dfrac{x+12-x}{x\left(x+12\right)}=\dfrac{7}{2700}\\ \Leftrightarrow\dfrac{12}{x^2+12x}=\dfrac{7}{2700}\\ \Leftrightarrow7x^2+84x-32400=0\)

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ko bt lm

ĐKXĐ: x∉{0;-2}

Ta có; \(\frac{270}{x+2}+\frac{7}{10}=\frac{270}{x}\)

=>\(\frac{270}{x}-\frac{270}{x+2}=\frac{7}{10}\)

=>\(\frac{270\left(x+2\right)-270x}{x\left(x+2\right)}=\frac{7}{10}\)

=>\(\frac{270x+540-270x}{x\left(x+2\right)}=\frac{7}{10}\)

=>7x(x+2)=5400

=>\(7x^2+14x-5400=0\)

=>\(x^2+2x-\frac{5400}{7}=0\)

=>\(x^2+2x+1-\frac{5407}{7}=0\)

=>\(\left(x+1\right)^2=\frac{5407}{7}\)

=>\(x+1=\pm\sqrt{\frac{5407}{7}}\)

=>\(x=-1\pm\sqrt{\frac{5407}{7}}\) (nhận)

chiu thua

khó quá tui ko biết làm

a, x - 140 : 35= 270

x - 4 = 270

x = 274

b, (x - 140) : 35= 270

x - 140 = 9450

x = 9590

$\frac{270}{x-12}-\frac{270}{x}=\frac{2}{3}$

\(\Leftrightarrow-2x^2+24x+9720=0\)

\(\Leftrightarrow2x^2-24x-9720=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x_1=6+12\sqrt{34}\\x_2=6-12\sqrt{34}\end{matrix}\right.\) \(\left(tmđk\right)\)

\(x\times282-270\times x=1512\\ x\times\left(282-270\right)=1512\\ x\times12=1512\\ x=1512:12\\ x=126\)

x = 126

814

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\(\Leftrightarrow5x=1355+270\Leftrightarrow5x=1625\Leftrightarrow x=325\)

\(x5-270=1355\\ x5=1355+270\\ x5=1625\\ x=1625:5\\ x=325\)