so sanh 2 ps sau:1/a+1 va1/a-1
Những câu hỏi liên quan
tinh roi so sanh ket qua 2/1*3 va1/1-1/3
\(\frac{2}{1}\cdot3=6\)
\(\frac{1}{1}-\frac{1}{3}=1-\frac{1}{3}=\frac{2}{3}\)
6 > 2/3
Vậy ..... 2/1 * 3 > 1/1 - 1/3
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so sanh hai phan so 1/2439 va1/8313
n la 1 so tu nhien ,a/b la ps co ts a be hon msb.so sanh a/bva a+n/b+n
Vì \(\frac{a}{b}\)< 1 => a < b => a+n<b+n
=>an + ab < bn + ab
=>a(n +b) < b (n+a)
=>\(\frac{a}{b}\)<\(\frac{a+n}{b+n}\)
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so sanh 2 PS sau
\(\frac{7^{10}+1}{7^{10}-1}\)va \(\frac{7^{10}-1}{7^{10}-3}\)
Trong 3 so a,b,c co 1 so nguyen a,1 so nguyen duong va1 so bang 0
tim 3 so do biet :IaI=b^2(b-c)
so sanh 2 phan so sau
a=2017.2018-1 / 2017.2018
b=2018.2019-1 / 2018.2019
`a=(2017.2018-1)/(2017.2018)`
`=1-1/(2017.2018)`
`b=(2018.2019-1)/(2018.2019)`
`=1-1/(2018.2019)`
Vì `2017.2018<2019.2018`
`=>1/(2017.2018)>1/(2019.2018)`
`=>1-1/(2017.2018)<1-1/(2019.2018)`
Hay `a<b`
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a=2017.2018−12017.2018a=2017.2018-12017.2018
=1−12017.2018=1-12017.2018
b=2018.2019−12018.2019b=2018.2019-12018.2019
=1−12018.2019=1-12018.2019
Vì 2017.2018<2019.20182017.2018<2019.2018
⇒12017.2018>12019.2018⇒12017.2018>12019.2018
⇒1−12017.2018<1−12019.2018⇒1-12017.2018<1-12019.2018
Hay a<b
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so sanh cac ps sau:12/17 va7/15
cho 2 ps 13/14 va 15/16 hay so sanh 2 ps
so sanh 2 phan so sau :
A= a / 2a+1 va B= 3a+1 /6a+3
☺mong moi nguoi giup do
giả sử A>B
\(\Leftrightarrow\dfrac{a}{2a+1}>\dfrac{3x+1}{6x+3}\)
\(\Leftrightarrow\dfrac{3a}{3\left(2x+1\right)}>\dfrac{3x+1}{6x+3}\)
\(\Leftrightarrow\dfrac{3a}{6a+3}>\dfrac{3x+1}{6x+3}\)
\(\Leftrightarrow3a>3a+1\)
\(\Leftrightarrow0>1\) ( vô lí )
vậy \(\Rightarrow B>A\)
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giả sử A>B
⇔a2a+1>3x+16x+3⇔a2a+1>3x+16x+3
⇔3a3(2x+1)>3x+16x+3⇔3a3(2x+1)>3x+16x+3
⇔3a6a+3>3x+16x+3⇔3a6a+3>3x+16x+3
⇔3a>3a+1⇔3a>3a+1
⇔0>1⇔0>1 ( vô lí )
vậy ⇒B>A
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