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\(\frac{37}{35}:\frac{5}{4}:\frac{74}{25}\)
\(=\frac{37}{35}:\left(\frac{5}{4}\times\frac{74}{25}\right)\)
\(=\frac{37}{35}:\frac{37}{10}\)
\(=\frac{2}{7}\)
\(\frac{37}{35}:\frac{5}{4}:\frac{74}{25}\)
=\(\frac{37}{35}x\frac{4}{5}x\frac{25}{74}\)
\(=\left(\frac{37}{35}x\frac{25}{74}\right)x\frac{4}{5}\)
\(=\frac{1}{7}x\frac{5}{2}x\frac{4}{5}\)
\(=\frac{1x5x2x2}{7x2x5}\)
\(=\frac{2}{7}\)
a) 384 : 25 : 4 = 384 : ( 25 x 4 ) = 384 : 100 = 3,84
b) 380 : ( 38 x 2 ) = ( 380 : 38 ) : 2 = 10 : 2 = 5
\(a)152,693\cdot560+1526,93\cdot35+15,2693\cdot1900=1526,93\cdot56+1526,93\cdot35+1526,93\cdot19\)
\(=1526,93\cdot\left(56+35+19\right)\)
\(=1526,93\cdot110\) \(\)
\(=1526,93\cdot100+1526,93\cdot10\)
\(=152693+15269,3\)
\(=167962,3\)
\(b)12,6\cdot25+612\cdot2,5+26,2:0,04=126\cdot2,5+612\cdot2,5+262\cdot2,5\)
\(=2,5\cdot\left(126+612+262\right)\)
\(=2,5\cdot1000\)
\(=2500\)
\(\frac{5}{2}+\frac{5}{4}+\frac{5}{8}+\frac{5}{16}+\frac{5}{32}+\frac{5}{64}+\frac{5}{128}+\frac{5}{256}\)
\(\Rightarrow5-\frac{5}{2}+\frac{5}{2}-\frac{5}{4}+\frac{5}{4}-\frac{5}{8}+\frac{5}{8}-\frac{5}{16}+...+\frac{5}{128}-\frac{5}{256}\)
\(\Rightarrow5-\frac{5}{256}\)
\(\Rightarrow\frac{1275}{256}\)
Ta có 5/2 + 5/4 + 5/8 + 5/16 + 5/32 + 5/64 + 5/128 + 5/256
= 5- 5/2 + 5/2 - 5/4 + 5/4 - 5/8 + 5/8 - 5/16 + 5/16 - 5/32 + 5/32 - 5/64 + 5/64 - 5/128 + 5/128 - 5/256
= 5-5/256
= 1275/256
b ) Đặt \(A=\frac{5}{1.3}+\frac{5}{3.5}+\frac{5}{5.7}+...+\frac{5}{101.103}\)
\(\Rightarrow A=\frac{5}{2}\left(\frac{5}{1}-\frac{5}{3}+\frac{5}{3}-\frac{5}{5}+....+\frac{5}{101}-\frac{5}{103}\right)\)
\(\Rightarrow A=\frac{5}{2}\left(5-\frac{5}{103}\right)\)
35 × 34 + 34 × 38 + 65 × 75 + 65 × 45
= 34 × (35 + 38) + 65 × (75 + 45)
= 34 × 73 + 65 × 120
= 2482 + 7800
= 10282
~Study well~
#KSJ
3+15+7+29+5+12+21+35+47+38+42+8+1+45+49+43
=(3+47)+(5+45)+(7+43)+(29+21)+(12+38)+(15+35)+(1+49)+(8+42)
= 50 + 50 + 50 + 50 + 50 + 50 + 50 + 50
=50*8 = 400