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a: ||\(x:\left(-\frac23\right)+\frac12\) |+\(\frac56\) |\(\cdot\frac12=\frac34\)
=>||\(x:\left(-\frac23\right)+\frac12\) |\(+\frac56\) |\(=\frac34:\frac12=\frac32\)
mà \(\left|x:\left(-\frac23\right)+\frac12\right|+\frac56\ge\frac56\)
nên \(\left|x:\left(-\frac23\right)+\frac12\right|+\frac56=\frac32\)
=>\(\left|x:\left(-\frac23\right)+\frac12\right|=\frac32-\frac56=\frac96-\frac56=\frac46=\frac23\)
=>\(\left[\begin{array}{l}x:\left(-\frac23\right)+\frac12=\frac23\\ x:\left(-\frac23\right)+\frac12=-\frac23\end{array}\right.\Rightarrow\left[\begin{array}{l}x:\left(-\frac23\right)=\frac23-\frac12=\frac16\\ x:\left(-\frac23\right)=-\frac23-\frac12=-\frac46-\frac36=-\frac76\end{array}\right.\)
=>\(\left[\begin{array}{l}x=\frac16\cdot\left(-\frac23\right)=-\frac{2}{18}=-\frac19\\ x=-\frac76\cdot\left(-\frac23\right)=\frac{14}{18}=\frac79\end{array}\right.\)
a: \(\left|-\frac23x+\frac38\right|\cdot\left(-\frac85\right)=-\frac{8}{15}\)
=>\(\left|\frac23x-\frac38\right|=\frac{8}{15}:\frac85=\frac{5}{15}=\frac13\)
=>\(\left[\begin{array}{l}\frac23x-\frac38=\frac13\\ \frac23x-\frac38=-\frac13\end{array}\right.\Rightarrow\left[\begin{array}{l}\frac23x=\frac38+\frac13=\frac{17}{24}\\ \frac23x=-\frac13+\frac38=\frac{1}{24}\end{array}\right.\)
=>\(\left[\begin{array}{l}x=\frac{17}{24}:\frac23=\frac{17}{24}\cdot\frac32=\frac{17}{16}\\ x=\frac{1}{24}:\frac23=\frac{1}{24}\cdot\frac32=\frac{3}{48}=\frac{1}{16}\end{array}\right.\)

a: \(\frac{x-100}{24}+\frac{x-98}{26}+\frac{x-96}{28}=3\)
=>\(\left(\frac{x-100}{24}-1\right)+\left(\frac{x-98}{26}-1\right)+\left(\frac{x-96}{28}-1\right)=0\)
=>\(\frac{x-124}{24}+\frac{x-124}{26}+\frac{x-124}{28}=0\)
=>\(\left(x-124\right)\left(\frac{1}{24}+\frac{1}{26}+\frac{1}{28}\right)=0\)
=>x-124=0
=>x=124
b: \(\frac{x-1}{65}+\frac{x-3}{63}=\frac{x-5}{61}+\frac{x-7}{59}\)
=>\(\left(\frac{x-1}{65}-1\right)+\left(\frac{x-3}{63}-1\right)=\left(\frac{x-5}{61}-1\right)+\left(\frac{x-7}{59}-1\right)\)
=>\(\frac{x-66}{65}+\frac{x-66}{63}=\frac{x-66}{61}+\frac{x-66}{59}\)
=>\(\left(x-66\right)\left(\frac{1}{65}+\frac{1}{63}-\frac{1}{61}-\frac{1}{59}\right)=0\)
=>x-66=0
=>x=66
c: \(\frac{x-28-124}{2011}+\frac{x-124-2011}{28}+\frac{x-2011-28}{124}=3\)
=>\(\left(\frac{x-28-124}{2011}-1\right)+\left(\frac{x-124-2011}{28}-1\right)+\left(\frac{x-28-2011}{124}-1\right)=0\)
=>x-28-124-2011=0
=>x=2011+124+28
=>x=2163

bn lôi bài toán 6 hoặc lớp 5 ra đây hỏi bài à bn đây là chỗ hỏi bài dành cho hc sinh lớp 7 mà bn
Có 9999..99(gồm n chữ số 9)=[10^n-1].
Áp dụng:
11.11(2n chs 1)=\(\frac{10^{2n}-1}{9}\) , 111...1(n+1 chữ số 1)=\(\frac{10^{n+1}-1}{9}\),666....6(n chữ số 6)=\(\frac{10^{n}-1}{9}\) .6.
=> 11...1(2n chữ số 1)+111...1(n+1 chữ số 1)+666...66(n chữ số 1)+8=.....=\(\left(\frac{10^{n}+8}{3}\right)^2\) là 1 scp.