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\(\frac37+\frac{5}{13}+\frac{4}{13}\)
=\(\frac37+\left(\frac{5}{13}+\frac{4}{13}\right)\)
=\(\frac37+\frac{9}{13}\)
=\(\frac{39}{91}+\frac{63}{91}\)
=\(\frac{102}{91}\)
\(\left(\frac38+\frac{-3}{4}+\frac{7}{12}\right):\frac56+\frac12\)
=\(\left(\frac{9}{24}+\frac{-18}{24}+\frac{7}{24}\right)\times\frac65+\frac12\)
=\(\frac{5}{24}\times\frac65+\frac12\)
=\(\frac14+\frac12\)
=\(\frac14+\frac24\)
=\(\frac34\)
Trả lời
b)(1/3+12/67+13/41)-(79/67-28/41)
=1/3+12/67+13/41-79/67+28/41
=1/3+(12/67-79/67)+(13/41+28/41)
=1/3+(-67/67)+41/41
=1/3+(-1)+1
=1/3+0
=1/3.
\(1\frac57-\frac57\times\frac{2}{11}-\frac57\times\frac{9}{11}\)
=\(\frac57\times\left(1-\frac{2}{11}-\frac{9}{11}\right)\)
=\(\frac57\times\left(\frac{11}{11}-\frac{2}{11}-\frac{9}{11}\right)\)
=\(\frac57\times1\)
=\(\frac57\)
\(\frac{5}{11}\times\frac{18}{29}-\frac{5}{11}\times\frac{8}{29}+\frac{5}{11}\times\frac{19}{26}\)
=\(\frac{5}{11}\times\left(\frac{18}{29}-\frac{8}{29}+\frac{19}{29}\right)\)
=\(\frac{5}{11}\times1\)
=\(\frac{5}{11}\)
bài 1 a)
\(\frac{15}{7}\times\frac43+\frac63\)
=\(\frac{60}{21}+\frac63\)
=\(\frac{60}{21}+\frac{42}{21}\)
=\(\frac{102}{21}\)
=\(\frac{34}{7}\)
b)\(\frac{-13}{41}\times\frac{17}{11}\times\frac{11}{17}\)
=\(\frac{-13}{41}\times\left(\frac{17}{11}\times\frac{11}{17}\right)\)
=\(\frac{-13}{41}\times1\)
=\(\frac{-13}{41}\)
a, \(\frac{34}{13}-\frac{19}{28}-\frac{3}{31}=>\left(\frac{34}{13}-\frac{3}{31}\right)-\frac{19}{28}\)
= \(1-\frac{19}{28}=\frac{9}{28}\)
b, \(b,\frac{7}{3}-\left(\frac{11}{5}+\frac{4}{5}\right)\)
= \(\frac{7}{3}-3=>\frac{7}{3}-\frac{9}{3}=\frac{-2}{3}\)
c, \(\frac{18}{13}+\frac{55}{46}-\frac{5}{13}=\left(\frac{18}{13}-\frac{5}{13}\right)+\frac{55}{46}\)
= \(1+\frac{55}{46}=\frac{46}{46}+\frac{55}{46}=\frac{101}{46}\)
1/ \(\frac{9.5^{20}.27^9-3.9^{15}.25^9}{7.3^{29}.125^6-3.3^9.15^{19}}\)
\(=\frac{5^{20}.3^{29}-3^{31}.5^{18}}{7.3^{29}.5^{18}-3^{29}.5^{19}}=\frac{3^{29}.5^{18}.\left(25-9\right)}{3^{29}.5^{18}.\left(7-5\right)}=\frac{16}{2}=8\)
CÁC BÀI CÒN LẠI TƯƠNG TỰ HẾT NHÉ E
a) \(\left(\frac{1}{4}+-\frac{5}{13}\right)+\left(\frac{2}{11}+-\frac{8}{13}+\frac{3}{4}\right)\)
\(=\frac{2}{11}+\left(\frac{1}{4}+\frac{3}{4}\right)+\left(-\frac{5}{13}+-\frac{8}{13}\right)\)
\(=\frac{2}{11}+1+\left(-1\right)\)
\(=\frac{2}{11}+0\)
\(=\frac{2}{11}\)
b) \(\left(\frac{21}{31}+-\frac{16}{7}\right)+\left(\frac{44}{53}+\frac{10}{31}\right)+\frac{9}{53}\)
\(=-\frac{16}{7}+\left(\frac{21}{31}+\frac{10}{31}\right)+\left(\frac{44}{53}+\frac{9}{53}\right)\)
\(=-\frac{16}{7}+1+1\)
\(=-\frac{16}{7}+2\)
=\(-\frac{2}{7}\)
c) \(\frac{\frac{9}{45}-\frac{4}{13}-\frac{1}{3}}{\frac{3}{13}-\frac{1}{15}+\frac{2}{3}}\)
\(=-\frac{43}{81}\)
Baif: A=\(\frac{10n}{5n-3}=2+\frac{6}{5n-3}\)
để A nguyên thì 5n-3 = Ư(6)={-1;-2;-3;-6;1;2;3;6}
xét từng TH:
- 5n-3=-1=>n=2/5
- 5n-3=-2=>n=1/5
- 5n-3=-3=>n=0
- 5n-3=-6=>n=-3/5
- 5n-3=1=>n=4/5
- 5n-3=2=>n=1
- 5n-3=3=>n=6/5
- 5n-3=6=>n=9/5
b) A= \(\frac{10n}{5n-3}=2+\frac{6}{5n-3}\)
để A lớn nhất thì 5n-3 nhỏ nhất