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A=(6 : 35−116 x 67) : (415 x 1011+5211)A=(6 : 35−116 x 67) : (415 x 1011+5211)
A=(6 : 35−76 x 67) : (215 x 1011+5711)A=(6 : 35−76 x 67) : (215 x 1011+5711)
A=(10−1) : (4211+5711)A=(10−1) : (4211+5711)
A=9 : 9A=9 : 9
A=1
1a)\(\frac{5}{3}\)=\(\frac{5x4}{3x4}\)=\(\frac{20}{12}\); \(\frac{1}{4}\)=\(\frac{1x3}{4x3}\)=\(\frac{3}{12}\)
b)\(\frac{3}{8}\)=\(\frac{3x3}{8x3}\)=\(\frac{9}{24}\); \(\frac{7}{24}\)
c)\(\frac{1}{2}\)=\(\frac{1x15}{2x15}\)=\(\frac{15}{30}\); \(\frac{2}{3}\)=\(\frac{2x10}{3x10}\)=\(\frac{20}{30}\); \(\frac{3}{5}\)=\(\frac{3x6}{5x6}\)=\(\frac{18}{30}\)
2a)\(\frac{11}{8}\)>\(\frac{11}{9}\)
b)\(\frac{4}{9}\)<\(\frac{3}{5}\)
c)\(\frac{6}{5}\)>\(\frac{5}{6}\)
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10=55
2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18 + 20=110
1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19=100
k mk nha pạn hiền!
10 +1 = 11 có 10 số vậy thì 10 : 2 = 5 thì sẽ bằng 5x11 = 55
2 + 20 = 22 cũng có 10 số lấy 10 : 2 = 5 se bang 22 x5 = 110
1+19 = 20 , 10 : 2 = 5 , 20x5 = 100
\(a,=\frac{7-1}{1.3.7}+\frac{9-3}{3.7.9}+\frac{13-7}{7.9.13}+\frac{15-9}{9.13.15}\)\(+\frac{19-13}{13.15.19}\)
\(=\frac{1}{1.3}-\frac{1}{3.7}+\frac{1}{3.7}-\frac{1}{7.9}+\frac{1}{7.9}-\frac{1}{9.13}+\frac{1}{9.13}-\frac{1}{13.15}+\frac{1}{13.15}-\frac{1}{15.19}\)
\(=\frac{1}{1.3}-\frac{1}{15.19}=\frac{95}{285}-\frac{1}{285}=\frac{94}{285}\)
\(b,=\frac{1}{6}.\left(\frac{6}{1.3.7}+\frac{6}{3.7.9}+\frac{6}{7.9.13}+\frac{6}{9.13.15}+\frac{6}{13.15.19}\right)\)
làm giống như trên
\(c,=\frac{1}{8}.\left(\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+...+\frac{1}{48.49.50}\right)\)
\(=\frac{1}{16}.\left(\frac{2}{1.2.3}+\frac{2}{2.3.4}+\frac{2}{3.4.5}+...+\frac{2}{48.49.50}\right)\)
\(=\frac{1}{16}.\left(\frac{3-1}{1.2.3}+\frac{4-2}{2.3.4}+\frac{5-3}{3.4.5}+...+\frac{50-48}{48.49.50}\right)\)
\(=\frac{1}{16}.\left(\frac{1}{1.2}-\frac{1}{2.3}+\frac{1}{2.3}-\frac{1}{3.4}+\frac{1}{3.4}-\frac{1}{4.5}+...+\frac{1}{48.49}-\frac{1}{49.50}\right)\)
\(=\frac{1}{16}.\left(\frac{1}{2}-\frac{1}{2450}\right)=\frac{1}{16}.\left(\frac{1225}{2450}-\frac{1}{2450}\right)=\frac{153}{4900}\)
\(d,=\frac{5}{7}.\left(\frac{7}{1.5.8}+\frac{7}{5.8.12}+\frac{7}{8.12.15}+...+\frac{7}{33.36.40}\right)\)
\(=\frac{5}{7}.\left(\frac{8-1}{1.5.8}+\frac{12-5}{5.8.12}+\frac{15-8}{8.12.15}+...+\frac{40-33}{33.36.40}\right)\)
\(=\frac{5}{7}.\left(\frac{1}{1.5}-\frac{1}{5.8}+\frac{1}{5.8}-\frac{1}{8.12}+\frac{1}{8.12}-\frac{1}{12.15}+...+\frac{1}{33.36}-\frac{1}{36.40}\right)\)
\(=\frac{5}{7}.\left(\frac{1}{5}-\frac{1}{1440}\right)=\frac{5}{7}.\left(\frac{288}{1440}-\frac{1}{1440}\right)=\frac{41}{288}\)
P/S: . là nhân nha
c) \(\left(11+12+13+...+19\right).\left(6.8-48\right)=\left(11+12+13+...+19\right).\left(48-48\right)\)
\(=\left(11+12+13+...+19\right).0\)
\(=0\)
Hok "tuốt" nha^^
b) \(\left(500.9-250.18\right).\left(1+2+3+...+9\right)=\left(250.2.9-250.18\right).\left(1+2+...+9\right)\)
\(=\left(250.18-250.18\right).\left(1+2+3+...+9\right)\)
\(=0.\left(1+2+3+...+9\right)\)
\(=0\)
Hok tốt nha^^ (lần 2)
=(1+19)+(2+18)+(3+17)+(4+16)+(5+15)+(6+14)+(7+13)+(8+12)+(9+11)+10+20
=20x10+10
=210
a) ( 2011 - 125 x 8 : 4 ) x ( ( 48 : 8 x 6 )
= ( 2011 - 1000 : 4 ) x ( 6 x 6 )
= ( 2011 - 250 ) x 36
= 1761 x 36
= 63396
b) B = Không hiểu
c) C =
a, 1\(\dfrac{1}{6}\) + 1\(\dfrac{5}{12}\) + \(\dfrac{11}{6}\) + \(\dfrac{7}{12}\)
= ( 1 + \(\dfrac{1}{6}\)) + (1 + \(\dfrac{5}{12}\)) + \(\dfrac{11}{6}\) + \(\dfrac{7}{12}\)
= 1 + 1 +( \(\dfrac{1}{6}\) + \(\dfrac{11}{6}\)) + ( \(\dfrac{5}{12}\) + \(\dfrac{7}{12}\))
= 2+1+1
=4
b, \(\dfrac{3}{8}\) + 3\(\dfrac{11}{14}\)+1\(\dfrac{3}{14}\)+ \(\dfrac{5}{8}\)
= ( \(\dfrac{3}{8}\) + \(\dfrac{5}{8}\) ) + ( 3 + \(\dfrac{11}{14}\) ) + ( 1+ \(\dfrac{3}{14}\))
= 1 + 3 + 1 + ( \(\dfrac{11}{14}\) + \(\dfrac{3}{14}\))
= 5 + 1
=6
c, 2\(\dfrac{2}{9}\) + \(\dfrac{11}{18}\) + 1\(\dfrac{7}{9}\) + 1\(\dfrac{5}{6}\)
= (2 + \(\dfrac{2}{9}\) ) + ( 1 + \(\dfrac{7}{9}\) ) + \(\dfrac{11}{18}\) + \(\dfrac{11}{6}\)
= 2 + 1 + ( \(\dfrac{2}{9}\) + \(\dfrac{7}{9}\)) + \(\dfrac{11}{18}\) + \(\dfrac{33}{18}\)
=4 + \(\dfrac{22}{9}\)
= \(\dfrac{36}{9}\)+ \(\dfrac{22}{9}\)
= \(\dfrac{58}{9}\)
Mình cần gấp ạ!