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Lời giải:
a.
$\frac{5}{15}-\frac{1}{6}\times \frac{2}{5}=\frac{5}{15}-\frac{1}{15}=\frac{4}{15}$
b.
$\frac{8}{24}+\frac{3}{4}:\frac{1}{8}=\frac{1}{3}+6=\frac{19}{3}$
c.
$\frac{1}{7}: \frac{2}{8}-\frac{1}{7}=\frac{1}{7}\times 4-\frac{1}{7}$
$=\frac{1}{7}\times (4-1)=\frac{1}{7}\times 3=\frac{3}{7}$
a: \(A=0x^2y^4z+\dfrac{7}{2}x^2y^4z-\dfrac{2}{5}x^2y^4z=\dfrac{31}{10}x^2y^4z=\dfrac{31}{10}\cdot2^2\cdot\dfrac{1}{16}\cdot\left(-1\right)=-\dfrac{31}{40}\)
a: \(=\dfrac{7}{5}x^4z^3y=\dfrac{7}{5}\cdot2^4\cdot\left(-1\right)^3\cdot\dfrac{1}{2}=-\dfrac{56}{5}\)
b: \(=-xy^3\)
3A= 1+ \(\frac{1}{3}+\left(\frac{1}{3}\right)^2+...+\left(\frac{1}{3}\right)^7\)
2A= 1 - \(\left(\frac{1}{3}\right)^8\)
A= \(\frac{1-\left(\frac{1}{3}\right)^8}{2}\)
Vậy....
1/10 + 3/5 : 2/3
=1/10 + 9/10
=10/10
=1
\((\)6/8 -2/6\()\) x 1/2
=18/48 X 1/2
=3/7 x 1/2
=2/14
\(\dfrac{1}{10}\) + \(\dfrac{3}{5}\):\(\dfrac{2}{3}\)
= \(\dfrac{1}{10}\) + \(\dfrac{3}{5}\) \(\times\) \(\dfrac{3}{2}\)
= \(\dfrac{1}{10}\) + \(\dfrac{9}{10}\)
= \(\dfrac{10}{10}\)
= 1
( \(\dfrac{6}{8}\) - \(\dfrac{2}{6}\)) \(\times\) \(\dfrac{1}{2}\)
=( \(\dfrac{18}{24}\) - \(\dfrac{8}{24}\)) \(\times\) \(\dfrac{1}{2}\)
= \(\dfrac{10}{24}\) \(\times\) \(\dfrac{1}{2}\)
= \(\dfrac{5}{24}\)
2.Tính giá trị của biểu thức
( 1/2 : 0,5 - 1/4 : 0,25 + 1/8 : 0,125 - 1/10 :0,1 ) : ( 1+2+3+...+2016)
\(\left(\frac{1}{2}:0,5-\frac{1}{4}:0,25+\frac{1}{8}:0,125-\frac{1}{10}:0,1\right):\left(1+2+3+...+2016\right)\\ =\left(1-1+1-1\right):\left(1+2+3+...+2016\right)\\ =0:\left(1+2+3+...+2016\right)=0\)
\(E=\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{6}+\dfrac{1}{8}+\dfrac{1}{2}+\dfrac{1}{12}\)
\(E=\left(\dfrac{1}{2}+\dfrac{1}{2}\right)+\left(\dfrac{1}{3}+\dfrac{1}{6}\right)+\left(\dfrac{1}{8}+\dfrac{1}{12}+\dfrac{1}{24}\right)\)
\(E=\dfrac{2}{2}+\dfrac{3}{6}+\left(\dfrac{1}{8}+\dfrac{3}{24}\right)\)
\(E=1+\dfrac{1}{2}+\left(\dfrac{1}{8}+\dfrac{1}{8}\right)\)
\(E=\left(\dfrac{2}{2}+\dfrac{1}{2}\right)+\dfrac{2}{8}\)
\(E=\dfrac{3}{2}+\dfrac{1}{4}\)
\(E=\dfrac{6}{4}+\dfrac{1}{4}\)
\(E=\dfrac{7}{4}\)