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\(\begin{array}{l}a) - 2,5 = \frac{{ - 5}}{2} = \frac{{ - 10}}{4} = \frac{{ - 15}}{6} = ....\\b)2\frac{3}{4} = \frac{{11}}{4} = \frac{{22}}{8} = \frac{{33}}{{12}} = ...\end{array}\)
\(\left(5x-1\right)\left(\frac{2x-1}{3}\right)=0\)
\(\Leftrightarrow\left(\frac{\left(5x-1\right)\left(2x-1\right)}{3}\right)=0\)
\(\Leftrightarrow\left(5x-1\right)\left(2x-1\right)=0\)
\(\Rightarrow\orbr{\begin{cases}5x-1=0\\2x-1=0\end{cases}}\)\(\Rightarrow\orbr{\begin{cases}x=\frac{1}{5}\\x=\frac{1}{2}\end{cases}}\)
Vậy \(x=\frac{1}{5}\)hoặc\(x=\frac{1}{2}\)
a: \(=\left(1.25\right)^{16}\cdot8^{16}\cdot8=8\cdot10^{16}\)
b: \(=\left(\dfrac{5}{2}\right)^{13}\cdot4^{13}\cdot4^2=10^{13}\cdot4^2\)
c: \(=\left(0.25\right)^4\cdot8^4\cdot8^2=2^4\cdot8^2=64\cdot16=1024\)
d: \(=\left(\dfrac{1}{2}\right)^{15}\cdot2^{18}=2^3=8\)
e: \(=\left(\dfrac{1}{3}\cdot6\right)^7\cdot\left(\dfrac{1}{2}\right)^7\cdot\dfrac{1}{2}=2^7\cdot\left(\dfrac{1}{2}\right)^7\cdot\dfrac{1}{2}=\dfrac{1}{2}\)
2,5 x (-7 x 9 ) x 0,4
= (2,5 x 0,4 ) x ( -7 x 9)
= 1 x (-63)
= -63
Học tốt 'OωO
\(\begin{array}{l}a)\frac{{ - 6}}{{18}} + \frac{{18}}{{27}}\\ = \frac{{ - 1}}{3} + \frac{2}{3}\\ = \frac{1}{3}\\b)2,5 - ( - \frac{6}{9})\\ = \frac{{25}}{{10}} + \frac{6}{9}\\ = \frac{5}{2} + \frac{2}{3}\\ = \frac{{15}}{6} + \frac{4}{6}\\ = \frac{{19}}{6}\\c) - 0,32.( - 0,875)\\ = \frac{{ - 32}}{{100}}.( - \frac{{875}}{{1000}})\\ = \frac{{ - 8}}{{25}}.(\frac{{ - 7}}{8})\\ = \frac{8}{{25}}.\frac{7}{8}\\ = \frac{7}{{25}}\\d)( - 5):2\frac{1}{5}\\ = ( - 5):\frac{{11}}{5}\\ = ( - 5).\frac{5}{{11}}\\ = \frac{{ - 25}}{{11}}\end{array}\)
\(2,5x+9=3,75x-13,5\)
\(\Rightarrow3,75x-2,5x=9+13,5\)
\(\Rightarrow1,25x=22,5\)
\(\Rightarrow x=18\)
Bài làm:
Ta có: \(x.2,5+9=x.3,75-13,5\)
\(\Leftrightarrow\frac{5}{2}x+9=\frac{15}{4}x-13,5\)
\(\Leftrightarrow\frac{15}{4}x-\frac{5}{2}x=13,5+9\)
\(\Leftrightarrow\frac{5}{4}x=\frac{45}{2}\)
\(\Leftrightarrow x=\frac{45}{2}\div\frac{5}{4}\)
\(\Rightarrow x=18\)
\(...=\dfrac{5}{2}+\dfrac{6}{9}=\dfrac{5}{2}+\dfrac{2}{3}=\dfrac{15}{6}+\dfrac{4}{6}=\dfrac{19}{6}\)