A = 4/7.31 + 6/7.41 + 9/10.41 + 7/10.57 ; B = 7/19.31 + 5/19.43 + 3/23.43 + 11/23.57 Tính nhanh A/B
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YN
4 tháng 4 2022
`Answer:`
\(A=\frac{4}{7.31}+\frac{6}{7.41}+\frac{9}{10.41}+\frac{7}{10.57}\)
\(=\frac{5.4}{5.\left(7.31\right)}+\frac{5.6}{5.\left(7.41\right)}+\frac{5.9}{5.\left(10.41\right)}+\frac{5.17}{5.\left(10.57\right)}\)
\(=\frac{20}{35.31}+\frac{30}{35.41}+\frac{45}{50.41}+\frac{35}{50.57}\)
\(=5.\left(\frac{4}{35.31}+\frac{6}{35.41}+\frac{9}{50.41}+\frac{7}{50.57}\right)\)
\(=5.\left(\frac{1}{31}-\frac{1}{35}+\frac{1}{35}-\frac{1}{41}+\frac{1}{41}-\frac{1}{50}+\frac{1}{50}-\frac{1}{57}\right)\)
\(=5.\left(\frac{1}{31}-\frac{1}{57}\right)\)
\(=5.\frac{26}{1767}\)
\(=\frac{130}{1767}\)
PT
2
TB
15 tháng 6 2017
A= 5 x (4/31.7.5 + 6/7.5.41 + 9/41.10.5 + 7/ 10.5.57 + 1958/57.403.5)
= 5 x (4/31.35 + 6/35.41 + 9/41.50 + 7/50.57 + 1958/57.2015)
=5 x (1/31 - 1/35 + 1/35 - 1/41 + 1/41 - 1/50 + 1/50 - 1/57 + 1/57 - 1/2015)
= 5 x (1/31 - 1/2015)
= 5 x (65/2015 - 1/2015)
= 5 x 64/2015
= 320/2015 = 64/403
KK
0
MV
0
PH
1
24 tháng 5 2016
\(\frac{A}{5}=\frac{4}{35.31}+\frac{6}{35.41}+\frac{9}{50.41}+\frac{7}{50.57}=\frac{35-31}{35.31}+\frac{41-35}{35.41}+\frac{50-41}{50.41}+\frac{57-50}{50.57}\)
\(\frac{A}{5}=\frac{1}{31}-\frac{1}{35}+\frac{1}{35}-\frac{1}{41}+\frac{1}{41}-\frac{1}{50}+\frac{1}{50}-\frac{1}{57}=\frac{1}{31}-\frac{1}{57}\)=> A = 5. \(\left(\frac{1}{31}-\frac{1}{57}\right)\)
\(\frac{B}{2}=\frac{7}{38.31}+\frac{5}{38.43}+\frac{3}{43.46}+\frac{11}{46.57}=\frac{38-31}{31.38}+\frac{43-38}{38.43}+\frac{46-43}{43.46}+\frac{57-46}{46.57}\)
\(\frac{B}{2}=\frac{1}{31}-\frac{1}{38}+\frac{1}{38}-\frac{1}{43}+\frac{1}{43}-\frac{1}{46}+\frac{1}{46}-\frac{1}{57}=\frac{1}{31}-\frac{1}{57}\)=> B = 2.\(\left(\frac{1}{31}-\frac{1}{57}\right)\)
A/B = 5/2
NT
0
PM
1
LT
11 tháng 8 2017
A = \(\frac{4}{7}.31+\frac{6}{7}.41+\frac{9}{10}.41+\frac{7}{10}.57\)
= \(\left[\left(\frac{4}{7}+\frac{6}{7}\right).\left(31+41\right)\right]+\left[\left(\frac{9}{10}+\frac{7}{10}\right).\left(41+57\right)\right]\)
= \(\frac{10}{7}.72+\frac{8}{5}.98\)
= \(\left(\frac{10}{7}+\frac{8}{5}\right).\left(72+98\right)\)
= \(\left(\frac{50}{35}+\frac{56}{35}\right).170\)
= \(\frac{106}{35}.170\)
= \(\frac{3604}{7}\)
B = \(\frac{7}{19}.31+\frac{5}{19}.43+\frac{3}{23}.43+\frac{11}{23}.57\)
= \(\left[\left(\frac{7}{19}+\frac{5}{19}\right).\left(31+43\right)\right]+\left[\left(\frac{3}{23}+\frac{11}{23}\right).\left(43+57\right)\right]\)
= \(\frac{12}{19}.74+\frac{14}{23}.100\)
= \(\left(\frac{12}{19}+\frac{14}{23}\right).\left(100+74\right)\)
= \(\left(\frac{276}{437}+\frac{266}{437}\right).174\)
= \(\frac{542}{437}.174\)
= \(\frac{79674}{437}\)
A : B = \(\frac{3604}{7}:\frac{19674}{437}=\frac{3604.437}{7.19674}=\frac{1802.2.437}{7.9837.2.}=\frac{1802.437}{7.9837}\)
N
7 tháng 4 2019
Đây là toán lớp 6.
=>1/5B= 4/7.5.31 +6/7.5.41+9/5.10.41+7/5.10.57+13/57.5.14
=>1/5B=4/31.35+6/35.41+....+13/57.70
=>1/5B=1/31-1/35+1/35-1/41+...+1/57-1/70
=>1/5B=1/31-1/70
=>1/5B=39/2170
=>B=39/2170:1/5
=>B=39/424
T
7 tháng 4 2019
Ta có:
\(\frac{B}{5}=\frac{4}{35.31}+\frac{6}{35.41}+\frac{9}{50.41}+\frac{7}{50.57}+\frac{13}{57.70}\)
\(=\frac{35-31}{35.31}+\frac{41-35}{35.41}+\frac{50-41}{50.41}+\frac{57-50}{50.57}+\frac{70-57}{57.70}\)
\(=\frac{1}{31}-\frac{1}{35}+\frac{1}{35}-\frac{1}{41}+\frac{1}{41}-\frac{1}{50}+\frac{1}{50}-\frac{1}{57}+\frac{1}{57}-\frac{1}{70}\)
\(=\frac{1}{31}-\frac{1}{70}\)
\(\rightarrow B=5\cdot\left(\frac{1}{31}-\frac{1}{70}\right)\)
\(=5\cdot\frac{39}{2170}\)
\(=\frac{39}{434}\)
Vậy B=\(\frac{39}{434}\)
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
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