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a: \(\frac{3^{10}\cdot\left(-5\right)^{21}}{\left(-5\right)^{20}\cdot3^{12}}=\frac{-3^{10}\cdot5^{21}}{3^{12}\cdot5^{20}}=\frac{-5}{3^2}=-\frac59\)
b: \(\frac{-11^5\cdot13^7}{11^5\cdot13^8}=\frac{-11^5}{11^5}\cdot\frac{13^7}{13^8}=-\frac{1}{13}\)
c: \(2^{10}\cdot3^{10}-2^{10}\cdot3^9\)
\(=2^{10}\cdot3^9\cdot\left(3-1\right)\)
\(=2^{11}\cdot3^9\)
Ta có: \(\frac{2^{10}\cdot3^{10}-2^{10}\cdot3^9}{2^9\cdot3^{10}}\)
\(=\frac{2^{11}\cdot3^9}{2^{10}\cdot3^9}=2\)
d: \(5^{11}\cdot7^{12}+5^{11}\cdot7^{11}\)
\(=5^{11}\cdot7^{11}\left(7+1\right)=5^{11}\cdot7^{11}\cdot8\)
\(5^{12}\cdot7^{12}+9\cdot5^{11}\cdot7^{11}\)
\(=5^{11}\cdot7^{11}\left(5\cdot7+9\right)\)
\(=5^{11}\cdot7^{11}\left(35+9\right)=5^{11}\cdot7^{11}\cdot44\)
Ta có: \(\frac{5^{11}\cdot7^{12}+5^{11}\cdot7^{11}}{5^{12}\cdot7^{12}+9\cdot5^{11}\cdot7^{11}}\)
\(=\frac{5^{11}\cdot7^{11}\cdot8}{5^{11}\cdot7^{11}\cdot44}=\frac{8}{44}=\frac{2}{11}\)
a)\(\frac{3^{10}.\left(-5\right)^{21}}{\left(-5\right)^{20}.3^{12}}=\frac{-5}{9}\)
b)\(\frac{\left(-11\right)^5.13^7}{11^5.13^8}=-\frac{1}{13}\)
c)\(\frac{2^{10}.3^{10}-2^{10}.3^9}{2^9.3^{10}}=\frac{2^{10}.3^9\left(3-1\right)}{2^9.3^{10}}=2\)
d(\(\frac{5^{11}.7^{12}+5^{11}.7^{11}}{5^{12}.7^{12}+9.5^{11}.7^{11}}=\frac{5^{11}.7^{11}\left(7+1\right)}{5^{11}.7^{11}\left(35+9\right)}=\frac{1}{6}\)
a, -3/4 + 3/7 + -1/4 + 4/9 + 4/7
=\(\left(\frac{-3}{4}+\frac{-1}{4}\right)+\left(\frac{3}{7}+\frac{4}{7}\right)+\frac{4}{9}\)
=\(-1+1+\frac{4}{9}\)
=\(\frac{4}{9}\)
b, -7/9 x 4/11 + -7/9 x 7/11 + 5 và 7/9
\(=\frac{7}{9}x\frac{-4}{11}+\frac{7}{9}x\frac{-7}{11}+5x\frac{7}{9}\)
\(=\frac{7}{9}x\left(\frac{-4}{11}+\frac{-7}{11}+5\right)\)
\(=\frac{7}{9}x4\)
\(=\frac{28}{9}\)
c, ( 21/31 + 2013/6039 ) - ( 44/53 - 10/31) - /53
9+(-11)+21+9+(-10) 9-11+21+9-10. (-2) +21 +(-1). 18
-9 + (-11) + 21 + 9 +(-10)
= (-9 + 9) + [(-11) + 21] - 10
= 0 + 10 - 10
= 0
-9+(-11)+21+9+(-10)
Áp dụng quy tắc bỏ ngoặc đổi dấu, ta có:
-9-11+21+9-10
-9 và +9 là 2 số đối nhau có tổng bằng 0
-11-10=-21
-21+21=0(2 số đối)
Vì vậy:
-9-11+21-9-10=0
-9 + (-11) + 21 + 9 +(-10)
= (-9 + 9) + [(-11) + 21] - 10
= 0 + 10 - 10
= 0