\(\dfrac{8}{7}\)+419+\(\dfrac{-1}{7}\)
\(\dfrac{-4}{41}\)+(\(\dfrac{-37}{41}\)+2)
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\(\dfrac{-5}{12}+\dfrac{4}{37}+\dfrac{7}{12}-\dfrac{41}{37}+\dfrac{1}{2}\)
\(=\left(\dfrac{-5}{12}+\dfrac{7}{12}+\dfrac{1}{2}\right)+\left(\dfrac{4}{37}-\dfrac{41}{37}\right)\)
\(=\dfrac{2}{3}-1=-\dfrac{1}{3}\)
a: \(=\dfrac{-12}{7}\left(\dfrac{4}{35}+\dfrac{31}{35}\right)-\dfrac{2}{7}=\dfrac{-12}{7}-\dfrac{2}{7}=-2\)
b: =(-4)+(-4)+...+(-4)
=-4*25=-100
c: \(=157\cdot\left(-37\right)-41\cdot53+37\cdot157+51\cdot53\)
=10*53
=530
1: =5/13+8/13-20/41-21/41-5/17
=1-1-5/17=-5/17
2: =1/5+4/5-2/9-7/9+16/17
=16/17+1-1=16/17
3: =1/3-1/5+1/5-1/7+...+1/99-1/101
=1/3-1/101
=98/303
5.\(-\dfrac{3}{7}+\dfrac{5}{13}+\dfrac{-4}{12}=-\dfrac{103}{273}\)
b.\(-\dfrac{5}{21}+\dfrac{-2}{21}+\dfrac{8}{24}=\dfrac{-5-2}{21}+\dfrac{8}{24}=-\dfrac{7}{21}+\dfrac{8}{24}=-\dfrac{1}{3}+\dfrac{8}{24}=0\)
c.\(\dfrac{5}{13}+\dfrac{-5}{7}+\dfrac{-20}{41}+\dfrac{8}{13}+\dfrac{-21}{41}=\left(\dfrac{5}{13}+\dfrac{8}{13}\right)+\left(\dfrac{-20}{41}+\dfrac{-21}{41}\right)+-\dfrac{5}{7}=1-1-\dfrac{5}{7}=-\dfrac{5}{7}\)
Bài 3
a,26/100+0,009+41/100+0,24
0,26+0,09+0,41+0,24
(0,26+0,24)+(0,09+0,41)
0,5+0,5
=1
b,9+1/4+6+2/7+7+3/5+8+2/3+2/5+1/3+5/7+3/4
(9+6+7+8)+(2/7+5/7)+(1/4+3/4)+(3/5+2/5)+(2/3+1/3)
30+1+1+1+1
=34
Bài 4,5 khó quá mik ko bít lamf^^))
Bài 4: a, \(\dfrac{2008}{2009}\) < 1; \(\dfrac{10}{9}\) > 1
\(\dfrac{2008}{2009}\) < \(\dfrac{10}{9}\)
b, \(\dfrac{1}{a+1}\) và \(\dfrac{1}{a-1}\)
Ta có: a + 1 > a - 1 ⇒ \(\dfrac{1}{a+1}\) < \(\dfrac{1}{a-1}\)
`8/7+419-1/7`
`=7/7+419`
`=1+419=420`
`-4/41+(-37/41+2)`
`=-(4/41+37/41)+2`
`=-1+2`
`=1`
\(\dfrac{8}{7}+419+\dfrac{-1}{7}\)
=\(\left(\dfrac{8}{7}+\dfrac{-1}{7}\right)+419\)
=1+419
=420
\(\dfrac{-4}{41}+\left(\dfrac{-37}{41}+2\right)\)
=\(\dfrac{-4}{41}+\dfrac{-37}{41}+2\)
=\(\left(\dfrac{-4}{41}+\dfrac{-37}{41}\right)+2\)
=-1+2
=1