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\(\frac{6}{5}-\frac{1}{4}+\frac{4}{5}-\frac{3}{4}\)
\(=\left(\frac{6}{5}+\frac{4}{5}\right)-\left(\frac{1}{4}+\frac{3}{4}\right)\)
\(=2-1\)
\(=1\)
\(\frac{7}{9}-\frac{5}{12}+\frac{2}{9}-\frac{7}{12}\)
\(=\left(\frac{7}{9}+\frac{2}{9}\right)-\left(\frac{5}{12}+\frac{7}{12}\right)\)
\(=1-1\)
\(=0\)
các câu sau tương tự
A=1
B=0
C=ÂM 8/15
D=0
E=2
F=3/2
H=2/3
LẦN SAU CHO KHÓ SÍU NHA LỚP 5 CŨNG LÀM ĐC
a) Ta có: \(\dfrac{-5}{7}\left(\dfrac{14}{5}-\dfrac{7}{10}\right):\left|-\dfrac{2}{3}\right|-\dfrac{3}{4}\left(\dfrac{8}{9}+\dfrac{16}{3}\right)+\dfrac{10}{3}\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)
\(=\dfrac{-5}{7}\cdot\dfrac{3}{2}\cdot\dfrac{21}{10}-\dfrac{3}{4}\cdot\dfrac{56}{3}+\dfrac{10}{3}\cdot\dfrac{8}{15}\)
\(=\dfrac{-9}{4}-14+\dfrac{16}{9}\)
\(=\dfrac{-1621}{126}\)
b) Ta có: \(\dfrac{17}{-26}\cdot\left(\dfrac{1}{6}-\dfrac{5}{3}\right):\dfrac{17}{13}-\dfrac{20}{3}\left(\dfrac{2}{5}-\dfrac{1}{4}\right)+\dfrac{2}{3}\left(\dfrac{6}{5}-\dfrac{9}{2}\right)\)
\(=\dfrac{-17}{26}\cdot\dfrac{13}{17}\cdot\dfrac{-3}{2}-\dfrac{20}{3}\cdot\dfrac{3}{20}+\dfrac{2}{3}\cdot\dfrac{-33}{10}\)
\(=\dfrac{3}{4}-1-\dfrac{11}{5}\)
\(=-\dfrac{49}{20}\)
B={[5^10. 7^3 - 25^2 . 49^2] : [(125 . 7)^3+5^9 . 14^3]} - {[2^12-4^6 . 9^2] : [(2^2.3)^6+8^4 . 3^5]
Sửa đề: \(5^9\cdot49^2\)
\(=\dfrac{5^{10}\cdot7^3-5^9\cdot7^4}{5^9\cdot7^3+5^9\cdot14^3}-\dfrac{2^{12}-2^{12}\cdot3^4}{2^{12}\cdot3^6+2^{12}\cdot3^5}\)
\(=\dfrac{5^9\cdot7^3\left(5-7\right)}{5^9\cdot7^3\left(1+8\right)}-\dfrac{2^{12}\left(1-3^4\right)}{2^{12}\left(3^6+3^5\right)}=\dfrac{-2}{9}+\dfrac{80}{972}\)
=-34/243
\(\left(\dfrac{3}{7}\right)^2\cdot\left(-7\right)^4=\dfrac{9}{49}\cdot49^2=9\cdot49=441\)
\(\left(-11\right)^{12}\cdot\left(\dfrac{4}{11}\right)^4=11^{12}\cdot\dfrac{4^4}{11^4}=11^8\cdot4^4=54875873536\)
\(\left(-6\right)^8\cdot\left(\dfrac{5}{6}\right)^7=6^8\cdot\dfrac{5^7}{6^7}=6\cdot5^7=469750\)
4) \(\left(\dfrac{3}{7}\right)^2\cdot\left(-7\right)^4\)
\(=\left(\dfrac{3}{7}\right)^2\cdot\left[\left(-7\right)^2\right]^2\)
\(=\left(\dfrac{3}{7}\right)^2\cdot49^2\)
\(=\left(\dfrac{3}{7}\cdot49\right)^2\)
\(=\left(\dfrac{147}{7}\right)^2\)
\(=21^2\)
\(=441\)
5) \(\left(-11\right)^{12}\cdot\left(\dfrac{4}{11}\right)^6\)
\(=\left[\left(-11\right)^2\right]^6\cdot\left(\dfrac{4}{11}\right)^6\)
\(=121^6\cdot\left(\dfrac{4}{11}\right)^6\)
\(=\left(121\cdot\dfrac{4}{11}\right)^6\)
\(=44^6\)
6) \(6^8\cdot\left(\dfrac{5}{7}\right)^7\)
\(=6^8\cdot\dfrac{5^7}{6^7}\)
\(=\dfrac{6^8\cdot5^7}{6^7}\)
\(=6\cdot5^7\)
\(=469750\)
a: =-15/24-18/24+60/24
=27/24=9/8
b: =6/12-9/12-10/12-7/12=-20/12=-5/3
c: =17/2+3/7-5/3=305/42
c: =-3-2/3-10/9-25/3-5/6
=-10-19/9-5/6
=-180/18-38/18-15/18=-233/18
