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\(A=\left(\frac{21}{5}-\frac{3}{5}\right):\frac{16}{8}:\frac{9}{10}\)
\(A=\frac{18}{5}:\frac{16}{8}:\frac{9}{10}\)
\(A=\frac{18}{5}\times\frac{8}{16}\times\frac{10}{9}\)
\(A=\frac{9}{5}\times\frac{8}{8}\times\frac{10}{9}\)
\(A=\frac{72}{40}\times\frac{10}{9}\)
\(A=\frac{8}{4}\times\frac{1}{1}\)
\(A=\frac{8}{9}\)
\(B=\left(1\frac{1}{20}+\frac{36}{100}\right):\frac{84}{25}:\left(2+\frac{14}{16}\right)\)
\(B=\left(\frac{21}{20}+\frac{36}{100}\right):\frac{84}{25}:\left(\frac{32}{16}+\frac{14}{16}\right)\)
\(B=\left(\frac{105}{100}+\frac{36}{100}\right):\frac{84}{25}:\frac{46}{16}\)
\(B=\frac{141}{100}:\frac{84}{25}:\frac{46}{16}\)
\(B=\frac{141}{100}\times\frac{25}{84}\times\frac{16}{46}\)
\(B=\frac{141}{4}\times\frac{1}{84}\times\frac{16}{46}\)
\(B=\frac{141}{336}\times\frac{16}{46}\)
\(B=\frac{141}{21}\times\frac{1}{46}\)
\(B=\frac{141}{966}\)
a;[(0,4+1,15-9/20]:0,1]:(3 va 1/6 +2 va 1/3)
=(11/10:1/10):11/2
=11:11/2
=2
b,[0,25:(10,3-9,8)-3/4]:[(3/8+5/12-1/4):1/36.24]
=(0,25:53/24-3/4):(13/24:1/36.24)
=-135/212:4̉́̉̉68
=-15/11024
nho tik nha
2/3+1/3.(-4/9+5/6):7/12
=2/3+1/3.(-8/18+15/18):7/12
=2/3+1/3.7/18:7/12
=2/3+7/54:7/12
=2/3+7/54.12/7
=2/3+2/9
=6/9+2/9
=8/9
Mấy bài này bạn tách tử với mẫu ra rồi tính,chứ viết thì dài lắm.
Mình biết nhưng làm theo cách cô mình chỉ thì kết quả lại không chia hết .giống như bài A mình ra 72.100 (phần) 90, theo cô mình chỉ thì mình phải tách 90 ra thành 27x(..) nhưng ko chia được.
`5`
`a, -7/21 +(1+1/3)`
`=-7/21 + ( 3/3 + 1/3)`
`=-7/21+ 4/3`
`=-7/21+ 28/21`
`= 21/21`
`=1`
`b, 2/15 + ( 5/9 + (-6)/9)`
`= 2/15 + (-1/9)`
`= 1/45`
`c, (9-1/5+3/12) +(-3/4)`
`= ( 45/5-1/5 + 3/12)+(-3/4)`
`= ( 44/5 + 3/12)+(-3/4)`
`= 9,05 +(-0,75)`
`=8,3`
`6`
`x+7/8 =13/12`
`=>x= 13/12 -7/8`
`=>x=5/24`
`-------`
`-(-6)/12 -x=9/48`
`=> 6/12 -x=9/48`
`=>x= 6/12-9/48`
`=>x=5/16`
`---------`
`x+4/6 =5/25 -(-7)/15`
`=>x+4/6 =1/5 + 7/15`
`=> x+ 4/6=10/15`
`=>x=10/15 -4/6`
`=>x=0`
`----------`
`x+4/5 = 6/20 -(-7)/3`
`=>x+4/5 = 6/20 +7/3`
`=>x+4/5 = 79/30`
`=>x=79/30 -4/5`
`=>x= 79/30-24/30`
`=>x= 55/30`
`=>x= 11/6`
\(5)\)
\(A=\dfrac{-7}{21}+\left(1+\dfrac{1}{3}\right)\)
\(A=\dfrac{-7}{21}+\dfrac{4}{3}\)
\(A=\dfrac{-7}{21}+\dfrac{28}{21}\)
\(A=1\)
\(--------------\)
\(B=\dfrac{2}{15}+\left(\dfrac{5}{9}+\dfrac{-6}{9}\right)\)
\(B=\dfrac{2}{15}+\dfrac{-1}{9}\)
\(B=\dfrac{18}{135}+\dfrac{-15}{135}\)
\(B=\dfrac{1}{45}\)
\(------------\)
\(C=9-\dfrac{1}{5}+\dfrac{3}{12}+\dfrac{-3}{4}\)
\(C=\dfrac{44}{5}+\dfrac{3}{12}+\dfrac{-3}{4}\)
\(C=\dfrac{528}{60}+\dfrac{15}{60}+\dfrac{-3}{4}\)
\(C=\dfrac{181}{20}+\dfrac{-3}{4}\)
\(C=\dfrac{181}{20}+\dfrac{-15}{20}\)
\(C=\dfrac{83}{10}\)
\(6)\)
\(a)\) \(x+\dfrac{7}{8}=\dfrac{13}{12}\)
\(x=\dfrac{13}{12}-\dfrac{7}{8}\)
\(x=\dfrac{104}{96}-\dfrac{84}{96}\)
\(x=\dfrac{5}{24}\)
\(b)\) \(\dfrac{-6}{12}-x=\dfrac{9}{48}\)
\(\dfrac{-1}{2}-x=\dfrac{3}{16}\)
\(x=\dfrac{-1}{2}-\dfrac{3}{16}\)
\(x=\dfrac{-8}{16}-\dfrac{3}{16}\)
\(x=\dfrac{-11}{16}\)
\(c)\) \(x+\dfrac{4}{6}=\dfrac{5}{25}-\left(-\dfrac{7}{15}\right)\)
\(x+\dfrac{4}{6}=\dfrac{5}{25}+\dfrac{7}{15}\)
\(x+\dfrac{4}{6}=\dfrac{75}{375}+\dfrac{105}{375}\)
\(x+\dfrac{4}{6}=\dfrac{12}{25}\)
\(x=\dfrac{12}{25}-\dfrac{4}{6}\)
\(x=\dfrac{72}{150}-\dfrac{100}{150}\)
\(x=\dfrac{-14}{75}\)
\(d)\) \(x+\dfrac{4}{5}=\dfrac{6}{20}-\left(-\dfrac{7}{3}\right)\)
\(x+\dfrac{4}{5}=\dfrac{6}{20}+\dfrac{7}{3}\)
\(x+\dfrac{4}{5}=\dfrac{18}{60}+\dfrac{140}{60}\)
\(x+\dfrac{4}{5}=\dfrac{79}{30}\)
\(x=\dfrac{79}{30}-\dfrac{4}{5}\)
\(x=\dfrac{79}{30}-\dfrac{24}{30}\)
\(x=\dfrac{11}{6}\)
a/ A= 1-3+5-7+9-11+......+97-99
= -2+(-2)+(-2)+......+(-2)
= (-2).25=-50
b/B=-1-2-3-4-...-100
=-(1+2+3+4+...+100)
=-5050
c/C=1-2+3-4+5-6+......+99-100
= -1+(-1)+(-1)+.............+(-1)
=(-1).50=-50
d/D=1-2-3+4+5-6-7+8+9-....+94-95
= (1-2-3+4)+(5-6-7+8)+.......+(92-93-94+95)
= 0+0+0+...+0=0