So sánh các phân số:
a) \(\dfrac{-47}{53}\) và \(\dfrac{-4747}{5353}\)
b) \(\dfrac{-19}{21}\) và \(\dfrac{1}{50}\)
c) \(\dfrac{-31}{128}\) và \(\dfrac{55}{-212}\)
d) \(\dfrac{23456}{-23457}\) và \(\dfrac{-4321}{4320}\)
e) \(\dfrac{19^{16}+1}{19^{17}+1}\) và \(\dfrac{19^{15}+1}{19^{16}+1}\)
Akai Haruma Phùng Tuệ Minh Nguyễn Việt Lâm Nguyễn Trương Nguyen DƯƠNG PHAN KHÁNH DƯƠNG Truong Viet Truong Khôi Bùi Ánh Lê saint suppapong udomkaewkanjana
a) \(-\dfrac{47}{53}=\dfrac{-47\cdot101}{53\cdot101}=\dfrac{-4747}{5353}\)
b)\(\dfrac{-19}{21}< 0\)
\(\dfrac{1}{50}>0\)
\(\Rightarrow-\dfrac{19}{21}< \dfrac{1}{50}\)
c)\(\dfrac{-31\cdot\left(-212\right)}{128\cdot\left(-212\right)}=\dfrac{-6572}{212\cdot128}\)
\(\dfrac{55\cdot128}{128\cdot\left(-212\right)}=\dfrac{-7040}{128\cdot212}\)
\(\Rightarrow\dfrac{-31}{128}>\dfrac{55}{-212}\)
d)
\(\dfrac{23456}{-23457}>-1\)
\(\dfrac{-4321}{4320}< -1\)
\(\Rightarrow\dfrac{23456}{-23457}>\dfrac{-4321}{4320}\)
e)
Học năm lớp 6 , giờ quên rồi :)))
e ) \(A=\dfrac{19^{16}+1}{19^{17}+1};B=\dfrac{19^{15}+1}{19^{16}+1}\)
\(\Rightarrow19A=\dfrac{19^{17}+19}{19^{17}+1}=1+\dfrac{18}{19^{17}+1}\)
\(19B=\dfrac{19^{16}+19}{19^{16}+1}=1+\dfrac{18}{19^{16}+1}\)
Do \(\dfrac{18}{19^{16}+1}>\dfrac{18}{19^{17}+1}\)
\(\Rightarrow1+\dfrac{18}{19^{16}+1}>1+\dfrac{18}{19^{17}+1}\)
\(\Rightarrow19B>19A\)
\(\Rightarrow B>A\)
