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\(\frac{13}{21}\)+\(\frac{15}{13}\)+\(\frac{14}{5}\)
=\(\frac{845}{1365}\)+\(\frac{1575}{1365}\)+\(\frac{3822}{1365}\)
=\(\frac{6242}{1365}\)
Ta có:\(x.\frac{1}{5}+x.\frac{4}{5}=2\)
=>\(x.\frac{1}{5}+\frac{4}{5}=2\)
=>\(x.\frac{5}{5}=2\)
=>\(x.1=2\)
=>\(x=2:1\)
=>\(x=2\)
a,\(2-\frac{5}{7}+\frac{9}{21}\)
\(=2-\frac{154}{147}\)
\(=\frac{135}{147}\)
b, \(\frac{5}{8}\):\(3+\frac{25}{24}\)
\(=\frac{5}{24}+\frac{25}{24}\)
\(=\frac{30}{24}\)
75/100+18/21+19/32+1/4+3/21+13/32=3 NHA BN
1+2+3+5+8+13+21+34+55+89+144+233
= ( 2+3+5) +( 1+8+21) +( 13+34+233) + ( 55+89+144)
= 10 + 30 + 280 + 288
= 40+ 280 + 288
= 320 + 288
= 608
1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233
= (1 + 2 + 3) + (5 + 8 + 13) + (21 + 34 + 55) + (89 + 144 + 233)
= 3 x 2 + 13 x 2 + 55 x 2 + 233 x 2
= (3 + 13 + 55 + 233) x 2
= 304 x 2
= 608
\(\frac{9}{2}-\frac{8}{3}:\frac{2}{3}+\frac{1}{2}=\frac{9}{2}-4+\frac{1}{2}=\frac{1}{2}+\frac{1}{2}=1\)
\(\frac{12}{5}:\frac{4}{7}-\frac{1}{2}=\frac{21}{5}-\frac{1}{2}=\frac{37}{10}\)
A) 9/2 - 8/3 : 2/3 + 1/2 = 9/2 - 8/3 x 3/2 + 1/2
= 9/2 - 4 + 1/2
= 1/2 + 1/2
= 1.
B) 12/5 : 4/7 - 1/2 = 12/5 x 7/4 - 1/2
= 21/5 -1/2
= 21/10.