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A=\(7\frac{4}{15}-3\frac{2}{9}-2\frac{4}{15}\)
=\(7\frac{4}{15}-2\frac{4}{15}-3\frac{2}{9}\)
= \(5-3\frac{2}{9}\)
= \(5-\frac{29}{9}\)
= \(\frac{45}{9}-\frac{29}{9}\)
= \(\frac{11}{9}\)
=\(1\frac{2}{9}\)

\(A=\frac{15.3^{11}+4.27^4}{9^7}=\frac{3.5.3^{11}+2^2.\left(3^3\right)^4}{\left(3^2\right)^7}=\frac{3^{12}.5+2^2.3^{12}}{3^{14}}\)
\(=\frac{3^{12}\left(5+4\right)}{3^{14}}=\frac{3^{12}.9}{3^{14}}\)
\(=\frac{3^{12}.3^2}{3^{14}}=\frac{3^{14}}{3^{14}}=1\)
Vậy giá trị biểu thức A là 1.
\(A=\frac{15.3^{11}+4.27^4}{9^7}\)
\(=\frac{3.5.3^{11}+4.3^{3.4}}{3^{2.7}}=\frac{3^{12}.5+3^{12}.4}{3^{14}}=\frac{3^{12}.5+4}{3^{14}}\)
\(=\frac{9}{3^2}=\frac{9}{9}=1\)
Vậy Giá trị biểu thức là 1

\(\frac{9^{10}\cdot27^7}{81^7\cdot3^{15}}=\frac{3^{20}\cdot3^{21}}{3^{28}\cdot3^{15}}=\frac{3^{41}}{3^{43}}=\frac{1}{9}\)
\(\frac{2^{10}\cdot3^{13}\cdot16^3}{4^{10}\cdot9^6}=\frac{2^{10}\cdot3^{13}\cdot2^{12}}{2^{20}\cdot3^{12}}=\frac{2^{22}\cdot3^{13}}{2^{20}\cdot3^{12}}=2^2\cdot3=12\)

a) 378
b) 3
c) 2
d) 2
e) \(\frac{8748}{1715}\)
Mình thấy bài e) bạn có ghi thiếu ko vậy.81^2 x;: hay là cộng trừ vậy?

A =\(\frac{2}{7}\times\frac{7}{15}-\frac{2}{3}\times\frac{5}{27}\) =\(\frac{14}{105}-\frac{10}{81}\)=\(\frac{2}{15}-\frac{10}{81}\)=\(\frac{162}{1215}-\frac{150}{1215}\)=\(\frac{12}{1215}\)
\(\frac{-4}{9}\times\frac{7}{15}+\frac{4}{9}\times\frac{5}{27}\)=\(\frac{-28}{135}+\frac{20}{243}\)=\(\frac{-6804}{32805}+\frac{2700}{32805}\)=\(\frac{-4104}{32805}\)=\(\frac{-152}{1215}\)
A=\(\frac{2}{7}\times\frac{7}{15}-\frac{2}{3}\times\frac{5}{27}\)chia cho\(\frac{-4}{9}\times\frac{7}{15}+\frac{4}{9}\times\frac{5}{27}\)
= \(\frac{12}{1215}:\frac{-152}{1215}\)
=\(\frac{12}{1215}\times\frac{1215}{-152}\)
=\(\frac{14580}{-184680}\)
\(\frac{14580}{-184680}\)rút gọn bằng\(\frac{-3}{38}\)

\(\frac{2^{19}.27^3+15^4.4^9.9^4}{6^9.2^{10}+12^{10}}\)
\(=\frac{2^{19}.\left(3^3\right)^3+\left(3.5\right)^4.\left(2^2\right)^9.\left(3^2\right)^4}{\left(2.3\right)^9.2^{10}+\left(2^2.3\right)^{10}}\)
\(=\frac{2^{19}.3^9+3^{12}.5^4.2^{18}}{2^{19}.3^9+2^{20}.3^{10}}\)
\(=\frac{2^{18}.3^9.\left(2+3^3+5^4\right)}{2^{19}.3^9.\left(1+2+3\right)}\)
\(=\frac{654}{2.6}\)
\(=\frac{109}{2}\)
Chúc bn học tốt !!!!

`5`
`a, -7/21 +(1+1/3)`
`=-7/21 + ( 3/3 + 1/3)`
`=-7/21+ 4/3`
`=-7/21+ 28/21`
`= 21/21`
`=1`
`b, 2/15 + ( 5/9 + (-6)/9)`
`= 2/15 + (-1/9)`
`= 1/45`
`c, (9-1/5+3/12) +(-3/4)`
`= ( 45/5-1/5 + 3/12)+(-3/4)`
`= ( 44/5 + 3/12)+(-3/4)`
`= 9,05 +(-0,75)`
`=8,3`
`6`
`x+7/8 =13/12`
`=>x= 13/12 -7/8`
`=>x=5/24`
`-------`
`-(-6)/12 -x=9/48`
`=> 6/12 -x=9/48`
`=>x= 6/12-9/48`
`=>x=5/16`
`---------`
`x+4/6 =5/25 -(-7)/15`
`=>x+4/6 =1/5 + 7/15`
`=> x+ 4/6=10/15`
`=>x=10/15 -4/6`
`=>x=0`
`----------`
`x+4/5 = 6/20 -(-7)/3`
`=>x+4/5 = 6/20 +7/3`
`=>x+4/5 = 79/30`
`=>x=79/30 -4/5`
`=>x= 79/30-24/30`
`=>x= 55/30`
`=>x= 11/6`
\(5)\)
\(A=\dfrac{-7}{21}+\left(1+\dfrac{1}{3}\right)\)
\(A=\dfrac{-7}{21}+\dfrac{4}{3}\)
\(A=\dfrac{-7}{21}+\dfrac{28}{21}\)
\(A=1\)
\(--------------\)
\(B=\dfrac{2}{15}+\left(\dfrac{5}{9}+\dfrac{-6}{9}\right)\)
\(B=\dfrac{2}{15}+\dfrac{-1}{9}\)
\(B=\dfrac{18}{135}+\dfrac{-15}{135}\)
\(B=\dfrac{1}{45}\)
\(------------\)
\(C=9-\dfrac{1}{5}+\dfrac{3}{12}+\dfrac{-3}{4}\)
\(C=\dfrac{44}{5}+\dfrac{3}{12}+\dfrac{-3}{4}\)
\(C=\dfrac{528}{60}+\dfrac{15}{60}+\dfrac{-3}{4}\)
\(C=\dfrac{181}{20}+\dfrac{-3}{4}\)
\(C=\dfrac{181}{20}+\dfrac{-15}{20}\)
\(C=\dfrac{83}{10}\)
\(6)\)
\(a)\) \(x+\dfrac{7}{8}=\dfrac{13}{12}\)
\(x=\dfrac{13}{12}-\dfrac{7}{8}\)
\(x=\dfrac{104}{96}-\dfrac{84}{96}\)
\(x=\dfrac{5}{24}\)
\(b)\) \(\dfrac{-6}{12}-x=\dfrac{9}{48}\)
\(\dfrac{-1}{2}-x=\dfrac{3}{16}\)
\(x=\dfrac{-1}{2}-\dfrac{3}{16}\)
\(x=\dfrac{-8}{16}-\dfrac{3}{16}\)
\(x=\dfrac{-11}{16}\)
\(c)\) \(x+\dfrac{4}{6}=\dfrac{5}{25}-\left(-\dfrac{7}{15}\right)\)
\(x+\dfrac{4}{6}=\dfrac{5}{25}+\dfrac{7}{15}\)
\(x+\dfrac{4}{6}=\dfrac{75}{375}+\dfrac{105}{375}\)
\(x+\dfrac{4}{6}=\dfrac{12}{25}\)
\(x=\dfrac{12}{25}-\dfrac{4}{6}\)
\(x=\dfrac{72}{150}-\dfrac{100}{150}\)
\(x=\dfrac{-14}{75}\)
\(d)\) \(x+\dfrac{4}{5}=\dfrac{6}{20}-\left(-\dfrac{7}{3}\right)\)
\(x+\dfrac{4}{5}=\dfrac{6}{20}+\dfrac{7}{3}\)
\(x+\dfrac{4}{5}=\dfrac{18}{60}+\dfrac{140}{60}\)
\(x+\dfrac{4}{5}=\dfrac{79}{30}\)
\(x=\dfrac{79}{30}-\dfrac{4}{5}\)
\(x=\dfrac{79}{30}-\dfrac{24}{30}\)
\(x=\dfrac{11}{6}\)
Sửa đề: \(A=\dfrac{-4}{9}\cdot\dfrac{2}{15}+\dfrac{4}{9}\cdot\dfrac{-13}{15}+\dfrac{4}{9}\)
\(=-\dfrac{4}{9}\left(\dfrac{2}{15}+\dfrac{13}{15}\right)+\dfrac{4}{9}\)
\(=-\dfrac{4}{9}+\dfrac{4}{9}=0\)
Em ghi lại đề được ko nhỉ, có vẻ đề ko chính xác chỗ 4/9+-13/15, phải là 4/9*-13/15 chứ