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\(\frac{10}{18}+\frac{4}{9}+\frac{26}{10}+\frac{12}{5}+\frac{9}{15}\)
\(=\frac{5}{9}+\frac{4}{9}+\frac{13}{5}+\frac{12}{5}+\frac{3}{5}\)
\(=\left(\frac{5}{9}+\frac{4}{9}\right)+\left(\frac{13}{5}+\frac{12}{5}+\frac{3}{5}\right)\)
\(=1+\frac{28}{5}\)
\(=\frac{33}{5}\)
Ta có:
a) \(\frac{10}{18}+\frac{4}{9}+\frac{26}{10}+\frac{12}{5}+\frac{9}{15}=\frac{5}{9}+\frac{4}{9}+\frac{13}{5}+\frac{12}{5}+\frac{9}{15}=1+1+\frac{9}{15}=1\frac{9}{15}\)
b)\(\frac{10}{18}+\frac{4}{9}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}=\left(\frac{5}{9}+\frac{4}{9}\right)+\left(\frac{16}{128}+\frac{8}{128}+\frac{4}{128}+\frac{2}{128}+\frac{1}{128}\right)\)
\(=1+\frac{31}{128}=1\frac{31}{128}\)
A)\(-\frac{3}{29}+\frac{16}{58}=-\frac{3}{29}+\frac{8}{29}=\frac{5}{29}\)
B)\(-\frac{1}{5}+\frac{5}{18}+-\frac{7}{9}=-\frac{1}{5}+\frac{5}{18}+-\frac{14}{18}=-\frac{1}{5}+-\frac{1}{2}\)\(=-\frac{2}{10}+-\frac{5}{10}=-\frac{7}{10}\)
C)\(-\frac{8}{18}+-\frac{15}{27}=-\frac{4}{9}+-\frac{5}{9}=-1\)
a,(11/15+4/15)+(5/7+2/7)
=1+1
=2
b,5/9x(1/2+6/4)
=5/9x2
=10/9
c,1/2:(7/8+9/8)
=1/2:2
=1
d,(17/10-7/10)+1/2
=1+1/2
=3/2
a) \(\frac{11}{15}+\frac{5}{7}+\frac{2}{7}+\frac{4}{15}=\left(\frac{11}{15}+\frac{4}{15}\right)+\left(\frac{5}{7}+\frac{2}{7}\right)\)
\(=2\)
b) \(\frac{5}{9}\times\frac{1}{2}\times\frac{5}{9}\times\frac{6}{4}=\frac{25}{81}\times\frac{3}{4}=\frac{25}{108}\)
c) \(\frac{7}{8}\div\frac{1}{2}+\frac{9}{8}\div\frac{1}{2}=\left(\frac{7}{8}+\frac{9}{8}\right)\div\frac{1}{2}\)
\(=2\div\frac{1}{2}=4\)
d) \(\frac{17}{10}+\frac{1}{2}-\frac{7}{10}=\left(\frac{17}{10}-\frac{7}{10}\right)+\frac{1}{2}\)
\(=1+\frac{1}{2}=\frac{3}{2}\)
a) \(\frac{11}{15}+\frac{5}{7}+\frac{2}{7}+\frac{4}{15}\)
\(=\left(\frac{11}{15}+\frac{4}{15}\right)+\left(\frac{5}{7}+\frac{2}{7}\right)\)
\(=1+1\)
\(=2\)
b) \(\frac{5}{9}.\frac{1}{2}.\frac{5}{9}.\frac{6}{4}\)
\(=\left(\frac{5}{9}\right)^2\left(\frac{1}{2}.\frac{6}{4}\right)\)
\(=\frac{25}{81}.\frac{3}{4}\)
\(=\frac{25}{108}\)
c) \(\frac{7}{8}:\frac{1}{2}+\frac{9}{8}:\frac{1}{2}\)
\(=\frac{7}{8}.2+\frac{9}{8}.2\)
\(=2\left(\frac{7}{8}+\frac{9}{8}\right)\)
\(=2.\frac{16}{8}\)
\(=2.2\)
\(=4\)
d) \(\frac{17}{10}+\frac{1}{2}-\frac{7}{10}\)
\(=\left(\frac{17}{10}-\frac{7}{10}\right)+\frac{1}{2}\)
\(=1+\frac{1}{2}\)
\(=\frac{2}{2}+\frac{1}{2}\)
\(=\frac{3}{2}\)
cái đầu =\(\frac{127}{128}\)vì:
1/2+1/4=3/4 mà 3/4 =1-1/4
1/2+1/4+1/8=7/8 mà 7/8=1-1/8
ta suy ra cách làm: Tổng dãy phân số trên bằng 1 trừ cho phân số cuối
=> Tổng dãy trên =1-1/128= 127/128
\(2009-\left(4\frac{5}{9}+x-7\frac{7}{18}\right):15\frac{2}{3}=2008\)
\(2009-\left(\frac{41}{9}+x-\frac{133}{18}\right):\frac{47}{3}=2008\)
\(\left(\frac{41}{9}+x-\frac{133}{18}\right):\frac{47}{3}=2009-2008\)
\(\left(\frac{41}{9}+x-\frac{133}{18}\right):\frac{47}{3}=1\)
\(\frac{41}{9}+x-\frac{133}{18}=1\cdot\frac{47}{3}\)
\(\frac{41}{9}+x-\frac{133}{18}=\frac{47}{3}\)
\(\frac{41}{9}+x=\frac{133}{18}+\frac{47}{3}\)
\(\frac{41}{9}+x=\frac{415}{18}\)
\(x=\frac{415}{18}-\frac{41}{9}\)
\(x=\frac{37}{2}\)
\(2009-\left(4\frac{5}{9}+x-7\frac{7}{18}\right)\div15\frac{2}{3}=2008\)
\(\left(4\frac{5}{9}+x-7\frac{7}{18}\right)\div15\frac{2}{3}=2009-2008\)
\(\left(-3\frac{3}{18}+x\right)\div15\frac{2}{3}=1\)
\(-3\frac{3}{18}+x=15\frac{2}{3}\)
\(x=15\frac{2}{3}+3\frac{3}{18}\)
\(x=15\frac{12}{18}+3\frac{3}{18}\)
\(x=18\frac{15}{18}\)
exactly 100%
\(\frac{7}{18}-\frac{4}{18}=\frac{3}{18}\) bạn tự thử lại = cách 3/18 + 4/18 = 7/18 ( kiểu thế nha )
\(\frac{8}{15}-\frac{2}{5}=\frac{8}{15}-\frac{6}{15}=\frac{2}{15}\)
\(1-\frac{5}{9}=\frac{9}{9}-\frac{5}{9}=\frac{4}{9}\)