Bài 6: So sánh phân số

\(\dfrac{1}{2}+\dfrac{-1}{5}+\dfrac{-5}{7}+\dfrac{1}{6}+\dfrac{-3}{35}+\dfrac{1}{3}\)

\(=\left(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{6}\right)+\left(\dfrac{-1}{5}+\dfrac{-5}{7}-\dfrac{3}{35}\right)\)

\(=\dfrac{3+2+1}{6}+\dfrac{-7-25-3}{35}\)

\(=\dfrac{6}{6}-\dfrac{35}{35}\)

=1-1

=0

c, \(\dfrac{3}{5}-x=\dfrac{5}{6}+\dfrac{13}{20}=\dfrac{100+78}{120}=\dfrac{178}{120}=\dfrac{89}{60}\Leftrightarrow x=-\dfrac{53}{60}\)

d, \(\left(x-\dfrac{1}{4}\right)^2=\dfrac{25}{64}\Leftrightarrow\left[{}\begin{matrix}x-\dfrac{1}{4}=\dfrac{5}{8}\\x-\dfrac{1}{4}=-\dfrac{5}{8}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{7}{8}\\x=-\dfrac{3}{8}\end{matrix}\right.\)

x + \(\dfrac{3}{4}=\dfrac{-6}{-8}\)

       x =\(\dfrac{-6}{-8}+\dfrac{3}{4}\)

      x=\(\dfrac{9}{16}\)

x+3/4=-6/-8

x+3/4=6/8

     x=6/8-3/4

     X=6/8-6/8

     x=0

x+3/4=-6/-8

x+3/4=6/8

     x=6/8-3/4

     X=6/8-6/8

     x=0

help 

\(\dfrac{5}{3}=\dfrac{35}{21}\)

\(\dfrac{8}{7}=\dfrac{24}{21}\)

do 35>24 nên \(\dfrac{5}{3}>\dfrac{8}{7}\)→a>b

\(ta.c\text{ó}:BCNN=21\\ \dfrac{5}{3}=\dfrac{5\cdot7}{3\cdot7}=\dfrac{35}{21};\dfrac{8}{7}=\dfrac{8\cdot3}{7\cdot3}=\dfrac{24}{21}\\ 35>24\\ \Rightarrow\dfrac{5}{3}>\dfrac{8}{7}hay.a>b\)

5/3>8/7

Có thể minh sai

A>B

\(\dfrac{4}{3}>1\)

\(-\dfrac{7}{3}< 1\)

Vậy a > b

\(a>b\)

Vì b là số âm nên sẽ nhỏ hơn a là số dương

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