\(\frac{4}{7x31}+\frac{6}{7x41}+\frac{9}{10x41}+\frac{7}{10x57}\)
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\(\frac{5}{7}\times x=\frac{20}{35\times31}+\frac{30}{35\times41}+\frac{45}{50\times41}+\frac{35}{50\times57}\)
\(\frac{5}{7}\times x=5\times\left(\frac{4}{35\times31}+\frac{6}{35\times41}+\frac{9}{50\times41}+\frac{7}{50\times57}\right)\)
\(\frac{5}{7}\times x=5\times\left(\frac{1}{31}-\frac{1}{35}+\frac{1}{35}-\frac{1}{41}+\frac{1}{41}-\frac{1}{50}+\frac{1}{50}-\frac{1}{57}\right)\)
\(\frac{5}{7}\times x=5\times\left(\frac{1}{31}-\frac{1}{57}\right)\)
\(x=5\times\frac{26}{1767}:\frac{5}{7}\)
\(x=7\times\frac{26}{1767}\)
\(x=\frac{182}{1767}\)
Vậy \(x=\frac{182}{1767}\)
Nếu thấy đúng thì cho mình vài cái h đúng nha!!!
\(A=\dfrac{20}{35\cdot31}+\dfrac{30}{35\cdot41}+\dfrac{45}{41\cdot50}+\dfrac{35}{50\cdot57}\)
=5(4/31*35+6/35*41+9/41*50+7/50*57)
=5(1/31-1/35+1/35-1/41+1/41-1/50+1/50-1/57)
=5*(1/31-1/57)
=130/1767
\(B=\dfrac{14}{38\cdot31}+\dfrac{10}{38\cdot43}+\dfrac{6}{43\cdot46}+\dfrac{22}{46\cdot57}\)
=2(7/31*38+5/38*43+3/43*46+11/46*57)
=2(1/31-1/38+1/38-1/43+...+1/46-1/57)
=>A/B=5/2
Đặt A là tên của biểu thức
\(A=\frac{4}{7.31}+\frac{6}{7.41}+\frac{9}{10.41}+\frac{7}{10.57}\)
\(=\frac{20}{31.35}+\frac{30}{35.41}+\frac{45}{41.50}+\frac{35}{50.57}\)
\(=5\left(\frac{4}{31.35}+\frac{6}{35.41}+\frac{9}{41.50}+\frac{7}{50.57}\right)\)
\(=5\left(\frac{1}{31}-\frac{1}{35}+\frac{1}{35}-\frac{1}{41}+\frac{1}{41}-\frac{1}{50}+\frac{1}{50}-\frac{1}{57}\right)\)
\(=5\left(\frac{1}{31}-\frac{1}{57}\right)=5\cdot\frac{26}{1767}=\frac{130}{1767}\)
130/1767