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a: \(\dfrac{6}{7}:\left(\dfrac{2}{5}\cdot\dfrac{6}{7}\right)\)
\(=\dfrac{6}{7}:\dfrac{12}{35}\)
\(=\dfrac{6}{7}\cdot\dfrac{35}{12}=\dfrac{6}{12}\cdot\dfrac{35}{7}=\dfrac{5}{2}\)
b: \(\dfrac{6}{7}+\dfrac{5}{7}:5-\dfrac{8}{9}\)
\(=\dfrac{6}{7}+\dfrac{1}{7}-\dfrac{8}{9}\)
\(=1-\dfrac{8}{9}=\dfrac{1}{9}\)
c: \(\dfrac{6}{7}+\dfrac{5}{8}\cdot\dfrac{1}{5}-\dfrac{3}{16}\cdot4\)
\(=\dfrac{6}{7}+\dfrac{1}{8}-\dfrac{3}{4}\)
\(=\dfrac{48+7-42}{56}=\dfrac{13}{56}\)
d: \(\dfrac{-1}{6}+\dfrac{2}{3}\cdot\dfrac{-3}{4}+\dfrac{4}{5}\)
\(=-\dfrac{1}{6}-\dfrac{1}{2}+\dfrac{4}{5}\)
\(=\dfrac{-5-15+24}{30}=\dfrac{4}{30}=\dfrac{2}{15}\)
(1.2.3.4.5.6.7.8.9) - (1.2.3.4.5.6.7.8) - (1.2.3.4.5.6.7.82)
= (1.2.3.4.5.6.7.8)(9 - 1 - 8)
= (1.2.3.4.5.6.7.8).0
= 0
Chúc bn học tốt! (Ez :D)
cái đầu tiên làm sao ra được
2x2+2=6
3x3-3=6
4 ko làm được
5:5+5=6
6x6:6=6
7-(7:7)=6
8,9,10 ko làm được
1)(-6-25).(-6+2)=-31*(-4)=124
2) \(\frac{7\cdot3-9}{-6}=\frac{12}{-6}=-2\)
3) (-5+19).(-4)=14*(-4)=-56
4) \(\frac{872}{-6\cdot2+4}=\frac{872}{-12+4}=\frac{872}{-8}=-109\)
5) -3*7-4*(-5)+19=-21+20+19=18
6)\(18-\frac{10}{2}-71=18-5-71=-58\)
7) \(\frac{115}{-5}\cdot\left(-3\right)-8=69-8=61\)
8) \(\left(6\cdot8-\frac{20}{5}\right)+3\cdot\left(-7\right)=48-4-21=23\)
( 1 + 1 + 1 ) ! = 6
2 + 2 + 2 = 6
3 . 3 - 3 = 6
\(\sqrt{4}\)+ \(\sqrt{4}\)\(\sqrt{4}\)= 6
5 +( 5 : 5) = 6
6 + 6 - 6 = 6
7 - (7:7) = 6
(\(\sqrt{8+\left(8:8\right)}\))! = 6
( 9 - 9 ) + ( \(\sqrt{9}\)) ! = 6
\(\sqrt{10-\left(10:10\right)}\)! = 6
bạn ủng hộ mknha! ddungs 100%
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\(A=\frac{5}{2.4.6}+\frac{5}{4.6.8}+...+\frac{5}{16.18.20}\)
\(4A=5.\left(\frac{4}{2.4.6}+\frac{4}{4.6.8}+...+\frac{4}{16.18.20}\right)\)
\(4A=5.\left(\frac{1}{2.4}-\frac{1}{4.6}+\frac{1}{4.6}-\frac{1}{6.8}+...+\frac{1}{16.18}-\frac{1}{18.20}\right)\)
\(4A=5.\left(\frac{1}{8}-\frac{1}{360}\right)\)
\(4A=5.\left(\frac{45}{360}-\frac{1}{360}\right)\)
\(4A=5.\frac{44}{360}\)
\(A=\frac{5.44}{360.4}\)
\(A=\frac{11}{72}\)
Tham khảo~
\(A=\frac{5}{2\cdot4\cdot6}+\frac{5}{4\cdot6\cdot8}+.....+\frac{5}{16\cdot18\cdot20}\)
\(\frac{4}{5}A=\frac{4}{2\cdot4\cdot6}+\frac{4}{4\cdot6\cdot8}+.........+\frac{4}{16\cdot18\cdot20}\)
\(\frac{4}{5}A=\frac{1}{2\cdot4}-\frac{1}{4\cdot6}+\frac{1}{4\cdot6}-\frac{1}{6\cdot8}+.........+\frac{1}{16\cdot18}-\frac{1}{18\cdot20}\)
\(\frac{4}{5}A=\frac{1}{2\cdot4}-\frac{1}{18\cdot20}\)
\(\frac{4}{5}A=\frac{1}{8}-\frac{1}{360}\)
\(\frac{4}{5}A=\frac{11}{90}\)
\(A=\frac{11}{90}:\frac{4}{5}=\frac{11}{72}\)
8/6+5/6-6/2=8/6+5/6-12/6=1/6