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a) \(\frac{3}{5}+\frac{4}{7}+\frac{2}{5}+\frac{1}{7}+\frac{2}{7}\)
\(=\left(\frac{3}{5}+\frac{2}{5}\right)+\left(\frac{4}{7}+\frac{1}{7}+\frac{2}{7}\right)\)
\(=\frac{5}{5}+\frac{7}{7}=1+1=2\)
a) \(\frac{3}{5}+\frac{4}{7}+\frac{2}{5}+\frac{1}{7}+\frac{2}{7}\)
\(=\left(\frac{3}{5}+\frac{2}{5}\right)+\left(\frac{4}{7}+\frac{1}{7}+\frac{2}{7}\right)\)
= 1 + 1
= 2
b) \(\frac{4}{9}+\frac{8}{9}+\frac{12}{9}+\frac{16}{9}+...+\frac{48}{9}+\frac{52}{9}+\frac{56}{9}\)
\(=\frac{4+8+12+16+...+48+52+56}{9}\)
Xét 4 + 8 + 12 + 16 + ... + 48 + 52 + 56
Số các số hạng là:
(56 - 4) : 4 + 1 = 14 (số)
4 + 8 + 12 + 16 + ... + 48 + 52 + 56 = (56 + 4) x 14 : 2 = 420
\(\frac{4+8+12+16+...+48+52+56}{9}=\frac{420}{9}=\frac{140}{3}\)
\(a,\frac{2}{5}+\frac{1}{6}+\frac{3}{5}\)
\(=\left(\frac{2}{5}+\frac{3}{5}\right)+\frac{1}{6}\)
\(=1+\frac{1}{6}\)
\(=\frac{7}{6}\)
Hok tốt!~
a)70=2*5*7
=>2*3*5/70=3/7
b)33*4=11*3*2*2=11*6*2
=>2*6*11/33*4=1
c)21*45=9*5*3*7
=>21*45/3*5*7*9=1
\(\frac{2\times3\times5}{70}\)
= \(\frac{2\times3\times5}{7\times2\times5}\)
= \(\frac{3}{7}\)
a) \(\left(56\times27+56\times35\right)\div62=56\times\left(27+35\right)\div62=56\times62\div62=56\)
b) \(\frac{0,18\times1230+0,9\times4567\times2+3\times5310\times6}{1+4+7+10+....+52+55-514}\)
\(=\frac{0,18\times1230+\left(0,9\times2\right)\times4567+\left(3\times6\right)\times5310}{1+4+5+.....+52+55-514}\)
\(=\frac{0,18\times1230+0,18\times4567+0,18\times5310}{1+4+7+...+52+55-514}\)
\(=\frac{0,18\times\left(1230+4567+5310\right)}{\left(55+1\right)\times55\div2-514}\)
\(=\frac{0,18\times11107}{971}=\frac{1999,26}{971}\)
mình ra cũng giống bạn Forever _ Alone nhé!!!Chẳng qua mình không biết viết phân số
a)\(\frac{2}{3}:\frac{4}{9}+\frac{1}{3}:\frac{4}{9}\)
=\(\frac{4}{9}:\left(\frac{2}{3}+\frac{1}{3}\right)\)
=\(\frac{4}{9}:1=\frac{4}{9}\)
b
\(3+\frac{2}{5}-\frac{3}{4}\times\frac{4}{5}\)
\(=3+\frac{2}{5}-\frac{3}{4}\)
\(=\frac{3\times20+2\times4-3\times5}{20}\)
\(=\frac{60+8-15}{20}\)
\(=\frac{68-15}{20}\)
\(=\frac{53}{20}\)
\(5-\frac{7}{9}+\frac{2}{3}-\frac{5}{6}:\frac{4}{9}\)
\(=5-\frac{7}{9}+\frac{2}{3}-\frac{45}{24}\)
\(=\frac{5\times72-7\times8+2\times24-45\times3}{72}\)
\(=\frac{360-56+48-135}{72}\)
\(=\frac{217}{72}\)
4/5 : 2/9 x 2/9 : 4/5
= 4/5 x 9/2 x 2/9 x 5/4
= ( 4/5 x 5/4 ) x ( 9/2 x 2/9 )
= 1x1
= 1
\(\frac{4}{5}:\frac{2}{9}\times\frac{2}{9}:\frac{4}{5}\)
\(=\frac{4}{5}\times\frac{9}{2}\times\frac{2}{9}\times\frac{5}{4}\)
\(=\left(\frac{4}{5}\times\frac{5}{4}\right)\times\left(\frac{2}{9}\times\frac{9}{2}\right)\)
\(=1\times1\)
\(=1\)
a. 2 5 + 3 7 + 3 5 + 4 7 = 2 5 + 3 5 + 3 7 + 4 7 = 5 5 + 7 7 = 1 + 1 = 2
b. 2 3 × 4 9 + 2 3 × 5 9 = 2 3 × 4 9 + 5 9 = 2 3 × 9 9 = 2 3 × 1 = 2 3