8/7+-6/7x4/11-4/11x5/11
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3/11 x 2 = 6/11
6/11 : 3/11 = 2
6/11 : 2 = 3/11
2/3 x 11 = 22/3
4/2 x 7 = 14
8/7 : 2/7 = 4
8/7 : 4 = 2/7
2/7 x 4 = 8/7
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= 4x4/3x7+ 4x4/7x11+ 4x4/11x15 = 4x(4/3x7 + 4/7x11+4/11x15) =4x(1/3-1/7+1/7-1/11+1/11-1/15) =4x(1/3-1/15)=4x4/15= 16/15.
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= 4x4/3x7+ 4x4/7x11+ 4x4/11x15
= 4x(4/3x7 + 4/7x11+4/11x15)
=4x(1/3-1/7+1/7-1/11+1/11-1/15)
=4x(1/3-1/15)=4x4/15= 16/15.
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a, \(\dfrac{38}{7}\) + ( \(\dfrac{16}{7}\) - \(\dfrac{5}{3}\))
= \(\dfrac{38}{7}\) + \(\dfrac{16}{7}\) - \(\dfrac{5}{3}\)
= \(\dfrac{54}{7}\) - \(\dfrac{5}{3}\)
= \(\dfrac{162}{21}\) - \(\dfrac{35}{21}\)
= \(\dfrac{127}{21}\)
b, \(\dfrac{29}{9}\) - ( \(\dfrac{14}{9}\) + \(\dfrac{11}{9}\) )
= \(\dfrac{29-14-11}{9}\)
= \(\dfrac{4}{9}\)
c, ( \(\dfrac{2}{7}\) + \(\dfrac{3}{8}\) + \(\dfrac{12}{7}\) + \(\dfrac{5}{8}\) ) - \(\dfrac{19}{63}\)
= ( \(\dfrac{2+12}{7}\) + \(\dfrac{3+5}{8}\)) - \(\dfrac{19}{63}\)
= \(\left(1+2\right)\) - \(\dfrac{19}{63}\)
= \(3-\dfrac{19}{63}\)
= \(\dfrac{189}{63}\) - \(\dfrac{19}{63}\)
= \(\dfrac{170}{63}\)
d, \(\dfrac{3}{7}\) . \(\dfrac{4}{9}\) + \(\dfrac{4}{9}\) . \(\dfrac{4}{7}\) - \(\dfrac{4}{9}\)
= \(\dfrac{4}{9}\) . ( \(\dfrac{3}{7}\) + \(\dfrac{3}{7}\) ) - \(\dfrac{4}{9}\)
= \(\dfrac{4}{9}\) . \(1-\dfrac{4}{9}\)
= \(\dfrac{4}{9}\) - \(\dfrac{4}{9}\)
= 0
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\(\left(\dfrac{3}{7}\right)^2\cdot\left(-7\right)^4=\dfrac{9}{49}\cdot49^2=9\cdot49=441\)
\(\left(-11\right)^{12}\cdot\left(\dfrac{4}{11}\right)^4=11^{12}\cdot\dfrac{4^4}{11^4}=11^8\cdot4^4=54875873536\)
\(\left(-6\right)^8\cdot\left(\dfrac{5}{6}\right)^7=6^8\cdot\dfrac{5^7}{6^7}=6\cdot5^7=469750\)
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) \(6^8\cdot\left(\dfrac{5}{7}\right)^7\)
\(=6^8\cdot\dfrac{5^7}{6^7}\)
\(=\dfrac{6^8\cdot5^7}{6^7}\)
\(=6\cdot5^7\)
\(=469750\)
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a: Dấu hiệu là thời gian giải bài
Số các giá trị là 10
b:
Mốt là 7 và 8
c: Phần lớn làm xong trong 7 hoặc 8 phút
\(\dfrac{8}{7}+\dfrac{-6}{7}.\dfrac{4}{11}-\dfrac{4}{11}.\dfrac{5}{11}\)
\(=\dfrac{8}{7}+\dfrac{4}{11}\left(-\dfrac{6}{7}-\dfrac{5}{11}\right)\)
\(=\dfrac{8}{7}+\dfrac{4}{11}.\dfrac{-101}{77}\)
\(=\dfrac{8}{7}+-\dfrac{404}{847}\)
\(=\dfrac{564}{847}\)