Bài 1 Thực hiện phép tính
A) 1+(-2)+3+(-4)+5+(-6) +.............................+2007+(2008)
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a: =1/6+14/6-3/6=12/6=2
b: =-13/8+5/4:(-5/4)
=-13/8-1=-21/8
c: =-3/8(2/5+14/5)
=-3/8*16/5
=-6/5
d: =5/34(1/4+11/9-2/9+29/4)
=5/34*(15/2+1)
=5/34*17/2
=5/4
a)
\(-12:\left(\dfrac{3}{4}-\dfrac{5}{6}\right)^2\)
\(=-12:\left(\dfrac{18}{24}-\dfrac{20}{24}\right)^2\)
\(=-12:\left(\dfrac{-1}{12}\right)^2\)
\(=-12:\dfrac{1}{144}\)
\(=-12\times\dfrac{144}{1}\)
\(=-1728\)
b)
\(\left(2^2:\dfrac{4}{3}-\dfrac{1}{2}\right)\times\dfrac{6}{5}-17\)
\(=\left(4\times\dfrac{3}{4}-\dfrac{1}{2}\right)\times\dfrac{6}{5}-17\)
\(=\left(3-\dfrac{1}{2}\right)\times\dfrac{6}{5}-17\)
\(=\dfrac{5}{2}\times\dfrac{6}{5}-17\)
\(=3-17\)
\(=-14\)
a)\(=-12:\left(-\dfrac{1}{12}\right)^2\)
\(=-12:\dfrac{1}{144}\)\(=-12.144=-1728\)
b)\(=\left(8:\dfrac{4}{3}-\dfrac{1}{2}\right).\dfrac{6}{5}-17\)
\(=\left(6-\dfrac{1}{2}\right).\dfrac{6}{5}-17\)
\(=\dfrac{11}{2}.\dfrac{6}{5}-17=\dfrac{33}{5}-17=\dfrac{33}{5}-\dfrac{85}{5}=-\dfrac{2}{5}\)
4:
a: =4/15-2,9+11/15=1-2,9=-1,9
b: \(=-36,75+3,7-63,25+6,3=10-100=-90\)
c: \(=6,5+3,5-\dfrac{10}{17}-\dfrac{7}{17}=10-1=9\)
d: \(=\dfrac{13}{25}\left(-39,1-60,9\right)=\dfrac{13}{25}\left(-100\right)=-52\)
e: =-5/12-7/12-3,7-6,3=-1-10=-11
f: =2,8(-6/13-7/13)-7,2=-2,8-7,2=-10
Ta có:1+2-3-4+5+6-7-8+9+10-...+2006-2007-2008+2009=1+(2-3-4+5)+(6-7-8+9)+...+(2006-2007-2008+2009)
=1+0+0+0+....+0
=1
Bài 1: Thực hiện các phép tính sau:
\(a)\)Chưa rỏ đề
\(b)\)\(5025\div5-25\div5\)
\(=\)\(1005-5\)
\(=\)\(1000\)
\(c)\)\(218-180\div2\div9\)
\(=\)\(218-10\)
\(=\)\(208\)
\(d)\)\(\left(328-8\right)\div32\)
\(=\)\(320\div32\)
\(=\)\(10\)
Bài 1:
a) ( Tôi không nhìn rõ đầu bài )
b) 5025 : 5 - 25 : 5
= ( 5025 - 25 ) : 5
= 5000 : 5
= 1000
c) 218 - 180 : 2 : 9
= 218 - 180 : ( 2 . 9 )
= 218 - 180 : 18
= 218 - 10
= 208
d) ( 328 - 8 ) : 32
= 320 : 32
= 10
\(a,\dfrac{2}{3}-\dfrac{5}{6}+\dfrac{3}{4}\)
\(=(\dfrac{2}{3}+\dfrac{3}{4})-\dfrac{5}{6}\)
\(=\dfrac{7}{12}\)
\(b,\dfrac{6}{7}.\dfrac{8}{13}+\dfrac{6}{13}.\dfrac{9}{7}-\dfrac{-4}{13}.\dfrac{6}{7}\)
\(=\dfrac{6}{7}.(\dfrac{8}{13}-\dfrac{4}{13})+(\dfrac{6}{13}.\dfrac{9}{7})\)
\(=(\dfrac{6}{7}.\dfrac{4}{13})+\dfrac{54}{91}\)
\(=\dfrac{24}{91}+\dfrac{54}{91}\)
\(=\dfrac{78}{91}=\dfrac{6}{7}\)
\(c,19.(-26)\)
\(=-494\)
a) `2/3 - 5/6 +3/4`
`=4/6-5/6+3/4`
`=-1/6+3/4`
`=-4/24+18/24`
`=14/24=7/12`
b) `6/7 .8/13 +6/13 .9/7 -4/13 .6/7`
`=6/7 .(8/13-4/13) + 6/13 .9/7`
`=6/7 . 4/13 + 6/13 . 9/7`
`= 6/13 .4/7 +6/13 .9/7`
`=6/13 . (4/7+9/7)`
`=6/13 . 13/7`
`=6/7`
c) `19.(-26)`
`=(1-20).(20+6)`
`=20+6-400-120`
`=-494`
=1-2+3-4+5-6+.........................+2007-2008 2008 số hạng
=(1-2)+(3-4)+(5-6)+............................+(2007-2008) 1004 nhóm
= (-1) +(-1) +(-1) +..............................+(-1) 1004 số hạng
= (-1).1004
= (-1004)