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a)\(\frac{5}{12}:\frac{2}{5}+\frac{7}{12}:\frac{2}{5}-\frac{1}{3}:\frac{2}{5}=\left(\frac{5}{12}+\frac{7}{12}-\frac{1}{3}\right):\frac{2}{5}=\frac{2}{3}:\frac{2}{5}=\frac{5}{3}.\)
b) \(\left(6,7+2,3+5,8\right):1,2=14,8:1,2=\frac{148}{10}:\frac{12}{10}=\frac{148}{12}=\frac{74}{6}=\frac{37}{3}\)
hk tốt!
=25/24 + 35/24 - 5/6
=60/24 - 5/6
=15/6 - 5/6
=15-5/6
=10/6
=5/3
mình chỉ biết í a thôi
a)13x3x32,27+67,63x39
=39x32,27+67,63x39
=39x(32,27+67,63)
=39x100
=3900
b,= 1- [ 1/2 x 1/3 x1/4 x..... x 1/100 ]
=1/2 x 2/3 x 3/4 x .......x 99/100
= 1x2x3x......x99 / 2x3x4x...... x100 [ rút gọn ]
= 1/100
135 - 5 (x+4)
135 - 5x + 20
=> 5x =135 - 20
5x = 115
x = 115:5
x = 23
135 - 5 ( x + 4 )
= 135 - 5x + 20
=> 5x = 135 - 20
5x = 115
x = 115 : 5
x = 23
\(3\frac{2}{5}=\frac{3\cdot5+2}{5}=\frac{17}{5}\)
\(2\frac{1}{7}=\frac{2\cdot7+1}{7}=\frac{15}{7}\)
\(8\frac{1}{6}=\frac{8\cdot6+1}{6}=\frac{49}{6}\)
\(2\frac{1}{2}=\frac{2\cdot2+1}{2}=\frac{5}{2}\)
\(3\frac{2}{5}\cdot2\frac{1}{7}=\frac{17}{5}\cdot\frac{15}{7}=\frac{51}{7}\)
\(8\frac{1}{6}:2\frac{1}{2}=\frac{49}{6}:\frac{5}{2}=\frac{49}{6}\cdot\frac{2}{5}=\frac{49}{15}\)
a ) \(1\frac{1}{2}+2\frac{1}{3}+3\frac{1}{6}-5\)
\(=\frac{3}{2}+\frac{7}{3}+\frac{19}{6}-\frac{5}{1}\)
\(=\frac{9}{6}+\frac{14}{6}+\frac{19}{6}-\frac{30}{6}\)
\(=\frac{23}{6}+\frac{19}{6}-\frac{30}{6}\)
\(=\frac{42}{6}-\frac{30}{6}\)
\(=\frac{12}{6}=2\)
b ) \(2\frac{2}{3}\times3\frac{3}{4}\div4\frac{4}{5}\)
\(=\frac{8}{3}\times\frac{15}{4}\div\frac{24}{5}\)
\(=\frac{120}{12}\div\frac{24}{5}\)
\(=\frac{120}{12}\times\frac{5}{24}\)
\(=\frac{600}{288}=\frac{25}{12}\)
c ) \(4\frac{1}{5}+5\frac{1}{3}-2\frac{2}{3}\times3\frac{1}{5}+\frac{9}{25}\div\frac{9}{20}\)
\(=\frac{21}{5}+\frac{16}{3}-\frac{8}{3}\times\frac{16}{5}+\frac{9}{25}\div\frac{9}{20}\)
\(=\frac{63}{15}+\frac{80}{15}-\frac{128}{15}+\frac{9}{25}\times\frac{20}{9}\)
\(=\frac{143}{15}-\frac{128}{15}+\frac{180}{225}\)
\(=\frac{15}{15}+\frac{12}{15}\)
\(=\frac{27}{15}=\frac{9}{5}\)
Ta có: \(L=\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right)....\left(1-\frac{1}{2004}\right)\)
\(\Rightarrow L=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.....\frac{2003}{2004}\)\(=\frac{1.2.3.4....2003}{2.3.4.....2004}=\frac{1}{2004}\)
VẬY \(L=\frac{1}{2004}\)
\(L=\left(1-\frac{1}{2}\right)x\left(1-\frac{1}{3}\right)x\left(1-\frac{1}{4}\right)x.....x\left(1-\frac{1}{2003}\right)\)
\(L=\frac{1}{2}x\frac{2}{3}x\frac{3}{4}x.....x\frac{2002}{2003}\)
\(L=\frac{1x2x3x4x....x2002}{2x3x4x5x.....x2003}=\frac{1}{2003}\)
1.
a) 5/8 x 4/10 + 2/3 =
= 1/4+ 2/3 = 11/12
b)5/12 x 4/7+5/12 x3/7
=5/12 x (4/7 +3/7)
=5/12 x1 = 5/12
c)(4/5 + 3/10 - 1/5 ) x 6 : 4/7
= ( 8/10 + 3/10 + 2/10) x 6 x 7/4
=13/10 x 21/2
=273/20
2.
5/8 và 3/2
ta có 5/8 =10/16 ; 3/2 =24 /16
vì 24 /16 >10 /16 nên 3/2 > 5/8
b. tương tự như câu a nha
c 418/417 và 925 /926
418/417 > 1 ; 925 /926 < 1
vì 418 /417 >1 mà 925/926 < 1 nên 418 / 417 > 925 /926
chúc bạn học tốt nha !
hok bé ơi
t lớp 7 r k lo ở lại