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#)Giải :
A, \(\frac{254x399-145}{254+399x253}\)
\(=\frac{253x399+399-145}{254+399x253}\)
\(=\frac{253x399+254}{254+399x253}\)
\(=1\)
B, \(\frac{5932+6001x5931}{5931x6001-69}\)
\(=\frac{5932+6001x5931}{\left(5931+1\right)x6001-69}\)
\(=\frac{5932+6001x5931}{5931x6001+6001-69}\)
\(=\frac{5932+6001x5932}{5932x6001+5932}\)
\(=1\)
#~Will~be~Pens~#
\(\frac{254x399-145}{254+399x253}=\frac{\left(253+1\right)x399-145}{254+399x253}=\frac{253x399+1x399-145}{254+399x253}=\frac{253x399+254}{254+399x253}\)
\(=1\)

\(\frac{254\times399-145}{254+399\times253}=\frac{253\times399+399-145}{254+399\times253}=\frac{253\times399+254}{254+399\times253}=1\)
\(\frac{254.399-145}{254+399.253}\)
\(=\frac{\left(253+1\right).399-145}{254+399.253}\)
\(=\frac{253.399+399-145}{254+399.253}\)
\(=\frac{253.399+254}{254+399.253}\)
\(=1\)

\(\frac{254\times399-145}{254+399\times253}\)
\(=\frac{\left(253+1\right)\times399-145}{399\times253+254}\)
\(=\frac{253\times399+399\times1-145}{399\times253+254}\)
\(=\frac{253\times399+399-145}{399\times253+254}\)
\(=\frac{253\times399+254}{399\times253+254}\)
\(=1\)

Bạn tự ghi lại đề nha !
A = \(\frac{1}{3}\)+ \(\left(\frac{1}{42}+\frac{1}{56}+...+\frac{1}{600}\right)\)
A = \(\frac{1}{3}\)+ \(\left(\frac{1}{6.7}+\frac{1}{7.8}+...+\frac{1}{24.25}\right)\)
A = \(\frac{1}{3}\)+ \(\left(\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+...+\frac{1}{24}-\frac{1}{25}\right)\)
A = \(\frac{1}{3}\)+ \(\left(\frac{1}{6}-\frac{1}{25}\right)\)
A = \(\frac{1}{3}\)+ \(\frac{19}{150}\)
A = \(\frac{23}{50}\).
Em xem lại đề bài nhé! có thể tham khảo bài dưới đây:
\(A=\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+...+\frac{1}{600}\)
\(=\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+...+\frac{1}{24.25}\)
\(=\frac{6-5}{5.6}+\frac{7-6}{6.7}+\frac{8-7}{7.8}+...+\frac{25-24}{25.24}\)
\(=\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+...+\frac{1}{24}-\frac{1}{25}\)
\(=\frac{1}{5}-\frac{1}{25}=\frac{4}{25}\)
Nếu đề bài không bị sai
\(A=\frac{1}{3}+\left(\frac{1}{42}+...+\frac{1}{600}\right)\)
\(=\frac{1}{3}+\left(\frac{1}{6.7}+\frac{1}{7.8}+...+\frac{1}{24.25}\right)\)
\(=\frac{1}{3}+\left(\frac{1}{6}-\frac{1}{25}\right)\)
Tự làm nốt nhé!
254-x:3=600:3
=>254-x:3=200
=>x:3=254-200=54
=>\(x=54\times3=162\)
?!