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a) Xét \(123+\left(-3\right)=120< 123\)
\(\Rightarrow123+\left(-3\right)< 123\)
b) Xét \(\left(-97\right)+7=\left(-90\right)>\left(-97\right)\)
\(\Rightarrow\left(-97\right)+7>\left(-97\right)\)
c) Xét \(\left(-55\right)+\left(-15\right)=\left(-70\right)< \left(-55\right)\)
\(\Rightarrow\left(-55\right)+\left(-15\right)< \left(-55\right)\)
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Đáp án :
93/140 > 63/97 > 31/49
ko có cách giải , tự tìm hiểu
ủng hộ tớ nha
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\(\frac{9^{99}-1}{-9^{98}+1}\) < \(\frac{-9^{98}-1}{9^{97+1}}\)
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\(\frac{2014^{61}}{2014^{60}}\)có phần thừa tới 1 là: \(\frac{2014}{2014^{60}}\)
\(\frac{2014^{98}}{2014^{97}}\)có phần thừa tới 1 là: \(\frac{2014}{2014^{97}}\)
Vì \(\frac{2014}{2014^{60}}>\frac{2014}{2014^{97}}\) nên \(\frac{2014^{61}}{2014^{60}}>\frac{2014^{98}}{2014^{97}}\)
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Ta có:A= \(\frac{10^{97}+1}{10^{98}+1}=10\cdot\left(\frac{10^{97}+1}{10^{98}+1}\right)=\frac{10^{98}+10}{10^{98}+1}\)=\(\frac{10^{98}+1+9}{10^{98}+1}\)=\(\frac{9}{10^{98}+1}+1\)
B=\(\frac{10^{96}+1}{10^{97}+1}=10\cdot\left(\frac{10^{96}+1}{10^{97}+1}\right)=\frac{10^{97}+10}{10^{97}+1}\)=\(\frac{10^{97}+1+9}{10^{97}+1}\)=\(\frac{9}{10^{97}+1}+1\)
Vì \(\frac{9}{10^{98}+1}+1\)< \(\frac{9}{10^{97}+1}+1\)\(\left(10^{98}+1>10^{97}+1\right)\)
Nên A<B
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a) \(\frac{8}{9}=1-\frac{1}{9}\)
\(\frac{108}{109}=1-\frac{1}{109}\)
Vì \(\frac{1}{9}>\frac{1}{109}\)
Nên \(1-\frac{1}{9}< 1-\frac{1}{109}\)
Vậy \(\frac{8}{9}< \frac{108}{109}\)
b)
\(\frac{97}{100}=\frac{97\cdot99}{100\cdot99}\)
\(\frac{98}{99}=\frac{98\cdot100}{99\cdot100}\)
\(\Rightarrow\frac{97}{100}< \frac{98}{99}\)
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Câu hỏi của Lê Thị Minh Trang - Toán lớp 6 - Học toán với OnlineMath
Xem bài 1 nhé !
Bài 1:
Xét vế phải :
\(P=\frac{99}{50}-\frac{97}{49}+...+\frac{7}{4}-\frac{5}{3}+\frac{3}{2}\)\(-1=2\)\(\left(\frac{99}{100}-\frac{97}{98}+...+\frac{7}{8}-\frac{5}{6}+\frac{3}{4}-\frac{1}{2}\right)\)
\(=2\left(\left(1-\frac{1}{100}\right)-\left(1-\frac{1}{98}\right)+...+\left(1-\frac{1}{4}\right)-\left(1-\frac{1}{2}\right)\right)\)
\(=2\left(\frac{1}{2}-\frac{1}{4}+\frac{1}{6}-\frac{1}{8}+...+\frac{1}{98}-\frac{1}{100}\right)\)
\(=1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{49}-\frac{1}{50}\)
\(=\left(1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{49}+\frac{1}{50}\right)-2\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{6}+...+\frac{1}{50}\right)\)
\(=\left(1+\frac{1}{2}+\frac{1}{2}+\frac{1}{4}+...+\frac{1}{25}+\frac{1}{26}+...+\frac{1}{50}\right)-\left(1+\frac{1}{2}+...+\frac{1}{25}\right)\)
\(=\frac{1}{26}+\frac{1}{27}+...+\frac{1}{49}+\frac{1}{50}\)
Đẳng thức được chứng tỏ là đúng
Bài 2 :
Đặt \(A'=\frac{3}{4}.\frac{4}{5}.\frac{7}{8}...\frac{4999}{5000}\)
Rõ ràng \(A< A'\)
SUY RA \(A^2< AA'=\frac{2}{50000}=\frac{1}{2500}=\left(\frac{1}{50}\right)^2\)
Nên \(A< \frac{1}{50}=0,02\)
Chúc bạn học tốt ( -_- )
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a)\(\frac{-23}{47}\)và\(\frac{-31}{61}\)
= -23x61= -1403
và
=-31x47= -1457
vậy là \(\frac{-23}{47}\)>\(\frac{-31}{61}\)
vì -1403 > -1457
câu b) cũng như vậy
(-97) + 7 = -( 97 -7) = -90. Vậy (-97) + 7 > (-97)