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a: 3/121=6/242<6/241
b: 16/52=4/23
60/115=5/23
63/175=9/25
mà 4/23<5/23<9/25
nên 16/52<60/115<63/175
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a)Ta có:\(\frac{n+2}{n+3}=1-\frac{1}{n+3}\)
+)Ta lại có:\(\frac{n+3}{n+4}=1-\frac{1}{n+4}\)
+)Ta thấy \(\frac{1}{n+3}>\frac{1}{n+4}\)
=>\(1-\frac{1}{n+3}< 1-\frac{1}{n+4}\)
Hay \(\frac{n+2}{n+3}< \frac{n+3}{n+4}\)
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a) \(\frac{120}{115}-1=\frac{5}{115}\) ; \(1-\frac{175}{170}=\frac{5}{170}\)
Vì \(\frac{5}{115}>\frac{5}{170}\) nên \(\frac{120}{115}<\frac{175}{170}\)
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em sử dụng phân số trung gian là 1/4 nhé; 16/63>16/64=1/4 = 5/20>5/22
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a) 25/26 < 89/98
b) 111/115 > 67/71
bấm máy tính ra số thập phân rồi so sánh nhé em trai :)
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a: 14/21=2/3=4/6
60/72=5/6
mà 4<5
nên 14/21<60/72
b: 38/133=2/7=16/56
129/344=3/8=21/56
mà 16<21
nên 38/133<129/344
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Bài 1:
a. \(\frac{-5}{12}\)và \(\frac{7}{-16}\), Đổi \(\frac{7}{-16}=\frac{-7}{16}\) b. \(\frac{-115}{133}\)và \(\frac{-6}{7}\)
Ta có Ta có
\(\frac{-5}{12}=\frac{-5.4}{12.4}=\frac{-20}{48}\) \(\frac{-6}{7}=\frac{-6.19}{7.19}=\frac{-114}{133}\)
\(\frac{-7}{16}=\frac{-7.3}{16.3}=\frac{-21}{48}\) Giữ nguyên \(\frac{-115}{133}\)
Mà \(\frac{-20}{48}>\frac{-21}{48}\Rightarrow\frac{-5}{12}>\frac{-7}{16}\) Mà \(\frac{-115}{133}< \frac{-114}{133}\Rightarrow\frac{-115}{133}< \frac{-6}{7}\)
Bài 2
a. 5x + 39 = 4 b. Ix-5I = 9
5x = 4 - 39 \(\Rightarrow\)x - 5 = 9 hoặc x - 5 = -9
5x = -35 TH1: x - 5 = 9 TH2: x - 5 = -9
x = (-35) : 5 x = 9 + 5 x = (-9) + 5
x = -7 x = 14 x = -4
Vậy x = -7 Vậy x = 14 hoặc x = -4