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\(\left(\frac{7}{19.31}+\frac{5}{19.43}+\frac{3}{23.43}+\frac{11}{23.57}\right):\left(\frac{1}{31}-\frac{1}{57}\right)\)
\(=\frac{7}{19}.\frac{7}{31}+\frac{5}{19}.\frac{5}{43}+\frac{3}{23}.\frac{3}{43}+\frac{11}{23}.\frac{11}{57}:\frac{1}{31}-\frac{1}{57}\)
\(=\frac{7}{19}+\frac{5}{19}.\frac{7}{31}+\frac{1}{31}:\frac{5}{43}-\frac{3}{43}.\frac{3}{23}+\frac{11}{23}.\frac{11}{57}+\frac{1}{57}\)
\(=\frac{12}{19}.\frac{8}{31}:\frac{2}{43}.\frac{7}{16}.\frac{4}{19}\)
\(=\frac{1204}{1767}\)
\(C=\frac{7}{19.31}+\frac{5}{19.43}+\frac{3}{23.43}+\frac{11}{23.57}\)
\(\frac{C}{2}=\frac{7}{31.38}+\frac{5}{38.43}+\frac{3}{43.46}+\frac{11}{46.57}\)
\(\frac{C}{2}=\frac{1}{31}-\frac{1}{38}+\frac{1}{38}-\frac{1}{43}+\frac{1}{43}-\frac{1}{46}+\frac{1}{46}-\frac{1}{57}\)
\(C=2\left(\frac{1}{31}-\frac{1}{57}\right)=2\cdot\frac{26}{1767}=\frac{52}{1767}\)
A=
7.31
4
+
7.41
6
+
10.41
9
+
10.57
7
⇒
5
A
=
35.31
4
+
35.41
6
+
50.41
9
+
50.57
7
\dfrac{A}{5}=\dfrac{1}{31}-\dfrac{1}{35}+\dfrac{1}{35}-\dfrac{1}{41}+\dfrac{1}{41}-\dfrac{1}{50}+\dfrac{1}{50}-\dfrac{1}{57}
5
A
=
31
1
−
35
1
+
35
1
−
41
1
+
41
1
−
50
1
+
50
1
−
57
1
\dfrac{A}{5}=\dfrac{1}{31}-\dfrac{1}{57}=\dfrac{26}{31.57}\Rightarrow A=\dfrac{130}{31.57}
5
A
=
31
1
−
57
1
=
31.57
26
⇒A=
31.57
130
à có ai chơi ngọc rồng không cho mk 1 nick có ddeeej là được
\(A=\frac{3}{1\cdot2}+\frac{3}{2\cdot3}+...+\frac{3}{49\cdot50}\)
\(A=3\left(\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+...+\frac{1}{49\cdot50}\right)\)
\(A=3\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{49}-\frac{1}{50}\right)\)
\(A=3\left(1-\frac{1}{50}\right)\)
\(A=3\cdot\frac{49}{50}=\frac{147}{50}\)