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NK
19 tháng 3 2023
Bài 1.
\(a,\dfrac{1}{3}+\dfrac{1}{4}=\dfrac{4}{12}+\dfrac{3}{12}=\dfrac{7}{12}\)
\(b,\dfrac{-2}{5}+\dfrac{7}{21}=\dfrac{-42}{105}+\dfrac{35}{105}=\dfrac{-77}{105}=\dfrac{-11}{15}\)
\(c,\dfrac{3}{8}+\dfrac{-5}{6}=\dfrac{18}{48}+\dfrac{-40}{48}=\dfrac{-22}{48}=\dfrac{-11}{24}\)
\(d,\dfrac{-3}{4}+\dfrac{2}{5}=\dfrac{-15}{20}+\dfrac{8}{20}=\dfrac{-7}{20}\)
\(e,\dfrac{1}{6}+\dfrac{-3}{2}=\dfrac{2}{12}+\dfrac{-18}{12}=\dfrac{16}{12}=\dfrac{4}{3}\)
\(f,\dfrac{-2}{5}+\dfrac{-4}{3}=\dfrac{-6}{15}+\dfrac{-20}{15}=\dfrac{-26}{15}\)
\(g,\dfrac{1}{8}+\dfrac{-3}{4}=\dfrac{4}{32}+\dfrac{-24}{32}=\dfrac{20}{32}=\dfrac{5}{8}\)
\(h,\dfrac{-3}{4}+\dfrac{3}{7}=\dfrac{-21}{28}+\dfrac{12}{28}=\dfrac{-9}{28}\)
\(i,\dfrac{-3}{4}+\dfrac{-4}{5}=\dfrac{-15}{20}+\dfrac{-16}{20}=\dfrac{-31}{20}\)
\(k,\dfrac{-5}{25}+\dfrac{-7}{14}=\dfrac{-70}{350}+\dfrac{-175}{350}=\dfrac{-245}{350}=\dfrac{-7}{10}\)
\(l,\dfrac{6}{21}+\dfrac{-3}{15}=\dfrac{90}{315}+\dfrac{-63}{315}=\dfrac{27}{315}=\dfrac{3}{35}\)
\(m,\dfrac{3}{4}-\dfrac{5}{8}+\dfrac{1}{2}=\dfrac{24}{32}-\dfrac{20}{32}+\dfrac{1}{2}=\dfrac{4}{32}+\dfrac{1}{2}=\dfrac{1}{8}+\dfrac{1}{2}=\dfrac{2}{16}+\dfrac{8}{16}=\dfrac{10}{16}=\dfrac{5}{8}\)
\(n,\dfrac{-3}{12}-\dfrac{1}{-4}+\dfrac{-2}{6}=\dfrac{-1}{4}-\dfrac{1}{-4}+\dfrac{-1}{3}=0+\dfrac{-1}{3}=\dfrac{-1}{3}\)
\(p,\dfrac{1}{3}+\dfrac{-3}{4}-\dfrac{5}{12}=\dfrac{4}{12}+\dfrac{-9}{12}-\dfrac{5}{12}=\dfrac{-5}{12}-\dfrac{5}{12}=\dfrac{-10}{12}=\dfrac{-5}{6}\)
Bài 2:
\(a,\dfrac{3}{5}+x=\dfrac{5}{6}\)
\(x=\dfrac{5}{6}-\dfrac{3}{5}\)
\(x=\dfrac{7}{30}\)
\(b,x-\dfrac{1}{4}=\dfrac{-5}{8}\)
\(x=\dfrac{-5}{8}+\dfrac{1}{4}\)
\(x=\dfrac{-3}{8}\)
\(c,x-\dfrac{2}{3}=\dfrac{7}{12}\)
\(x=\dfrac{7}{12}+\dfrac{2}{3}\)
\(x=\dfrac{5}{4}\)
\(d,x+\dfrac{-7}{15}=-1\dfrac{1}{20}\)
\(x=-1\dfrac{1}{20}-\dfrac{-7}{15}\)
\(x=\dfrac{-7}{12}\)
\(e,x-\dfrac{1}{2}=\dfrac{-3}{4}\)
\(x=\dfrac{-3}{4}+\dfrac{1}{2}\)
\(x=\dfrac{-1}{4}\)
\(f,x-\dfrac{3}{4}=\dfrac{1}{2}\)
\(x=\dfrac{1}{2}+\dfrac{3}{4}\)
\(x=\dfrac{5}{4}\)
\(g,x-\dfrac{1}{4}=\dfrac{5}{8}\cdot\dfrac{2}{3}\)
\(x-\dfrac{1}{4}=\dfrac{5}{12}\)
\(x=\dfrac{5}{12}+\dfrac{1}{4}\)
\(x=\dfrac{2}{3}\)
\(h,\dfrac{4}{5}-x=\dfrac{-8}{35}\)
\(x=\dfrac{4}{5}-\dfrac{-8}{35}\)
\(x=\dfrac{36}{35}\)
#YVA
7 tháng 4 2021
\frac{\frac{x}{-1}}{6}={\color{#c92786}{\frac{13}{-19}}}+\frac{8}{15}Đáp Án :𝑥 = 8 6 9 5
VH
16 tháng 8 2018
Câu 1:
[(4x+28).3+5.5]:5=35
[(4x+28).3+5.5]=35.5
(4x+28).3+25=175
(4x+28).3=175-25
(4x+28).3=150
4x+28=150:3
4x+28=50
4x=50-28
4x=22
x=22:4
x=5,5
LV
16 tháng 8 2018
a.\([\)(4x+28).3+5.5\(]\):5=35\(\Leftrightarrow\)4(x+7).3+25=175\(\Leftrightarrow\)4(x+7).3=150\(\Leftrightarrow\)4.(x+7)=50\(\Leftrightarrow\)x+7=\(\frac{25}{2}\)\(\Leftrightarrow\)x=\(\frac{11}{2}\)
b.720:\([\)41-(2x-5)\(]\)=40\(\Leftrightarrow\)41-(2x-5)=18\(\Leftrightarrow\)2x-5=23\(\Leftrightarrow\)x=14
c.3x+8x-30=25\(\Leftrightarrow\)11x=55\(\Leftrightarrow\)x=5
NN
2
ai giúp mik vs!!!
SP
1
VT
5
MS
11 tháng 5 2018
\(\frac{123}{321}\)x \(\frac{321}{123}\)= \(1\)( mình rút gọn phân số nha bạn,rút gọn tử này mẫu kia nhé.)
T mình nha
Chúc bạn học tốt ~<>
11 tháng 5 2018
\(\frac{123}{321}\cdot\frac{321}{123}=1\)
Bỏ hết tất cả con số giống nhau rồi làm theo như rút gọn vậy đó
TN
1
bài `2`
`a, x-1/2 =-3/4`
`=> x=-3/4 +1/2`
`=> x=-3/4 +2/4`
`=> x= -1/4`
`b, x+1/6 =-3/8`
`=> x=-3/8 - 1/6`
`=>x= -13/24`
`c, x-2/3 =3/5 -1/4`
`=> x-2/3 =7/20`
`=>x= 7/20 +2/3`
`=>x= 61/60`
`d, x-1/4 = 5/8 . 2/3`
`=> x-1/4 =5/12`
`=>x= 5/12 +1/4`
`=>x= 5/12 + 3/12`
`=>x= 2/3`
`e, 4/5 -x=-8/35`
`=>x= 4/5-(-8/35)`
`=>x= 4/5+8/35`
`=>x= 36/35`
`f, 11/12 x +3/4=1/6`
`=> 11/12 x =1/6-3/4`
`=> 11/12 x =-7/12`
`=>x=-7/12 : 11/12`
`=>x=-7/12 xx 12/11`
`=>x= -7/11`
`g, 2/9 - 2/7 x= 1/3`
`=> 2/7 x= 2/9- 1/3`
`=> 2/7 x=-1/9`
`=>x=-1/9 : 2/7`
`=>x=-1/9 xx 7/2`
`=>x= -7/18`
`h, x + (-7/15) = -1 1/20`
`=> x + (-7/15) =-21/20`
`=>x= -21/20 - (-7/15)`
`=>x= -21/20+7/15`
`=>x=-7/12`
`i, 3 1/5 x -7/10 = 1 3/5`
`=> 16/5 x -7/10 =8/5`
`=> 16/5 x =8/5 + 7/10`
`=> 16/5 x =23/10`
`=>x= 23/10 : 16/5`
`=>x= 23/10 xx 5/16`
`=>x= 23/32`
`b, x -1/2 = 3/4 : 3/2`
`=> x -1/2 = 3/4 xx 2/3`
`=> x -1/2 = 1/2`
`=>x= 1/2+1/2`
`=>x=1`
`k , 4/5 -1/2 x=1/10`
`=> 1/2 x=4/5 -1/10`
`=>1/2 x=7/10`
`=>x= 7/10 :1/2`
`=>x= 7/10 xx 2`
`=>x=7/5`
☹