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a) x+ \(\frac{4}{5}\)= \(\frac{4}{5}\)+ ( \(\frac{3}{7}\)+ \(\frac{3}{5}\))
x + \(\frac{4}{5}\)= \(\frac{4}{5}\)+ \(\frac{36}{35}\)
=> x = \(\frac{36}{35}\)
Vậy : x = \(\frac{36}{35}\)
b) \(\frac{4}{9}\)+\(\frac{8}{9}\)+ \(\frac{12}{9}\)+ ... + \(\frac{56}{9}\)
= \(\frac{4+8+12+...+56}{9}\)
Ta có : 4+8+12 + ... +56
Số các số hạng của dẫy số trên là : ( 56 -4) + 4 +1 = 14 ( số hạng )
=> Tổng trên = ( 4+56) x 14 : 2 = 420
=> \(\frac{4}{9}\)+ \(\frac{8}{9}\)+ ... + \(\frac{56}{9}\)= \(\frac{420}{9}\)= \(\frac{140}{3}\)
a)x=3/7+3/5=3x(1/7+1/5)=36/35
b)=(4+8+...+56)/9=(56+4)x14/9=280/3
3/5+4/7+2/5+1/7+2/7
=(3/5+2/5)+(4/7+1/7+2/7)
=1+1=2
4/9+8/9+12/9+16/9+48/9+56/9+44/9+52/9
=(4/9+16/9)+(8/9+12/9)+(48/9+52/9)+(56/9+44/9)
=20/9+20/9+100/9+100/9
=240/9
=80/3
HT
\(a,\frac{3}{5}+\frac{4}{7}+\frac{2}{5}+\frac{1}{7}+\frac{2}{7}=\left(\frac{3}{5}+\frac{2}{5}\right)+\left(\frac{4}{7}+\frac{1}{7}+\frac{2}{7}\right)=1+1=2\)
\(b,\frac{4}{9}+\frac{8}{9}+\frac{12}{9}+\frac{16}{9}+\frac{48}{9}+\frac{56}{9}+\frac{44}{9}+\frac{52}{9}\)
Phần này bạn xem lại đầu bài nhé!
( 1/10 + 2/9 + 3/8 + 4/7 + 5/6 + 1/6 + 3/7 + 5/8 + 7/9 + 9/10 ) * 48
= [ ( 1/10 + 9/10 ) + ( 2/9 + 7/9 ) + ( 3/8 + 5/8 ) + ( 4/7 + 3/7 ) + ( 5/6 + 1/6 ) ] * 48
=( 1 + 1 + 1 + 1 + ) *48
=5 * 48
= 240
a)\(8-\frac{3}{5}=\frac{40}{5}-\frac{3}{5}=\frac{37}{5}\)
b)\(\frac{24}{15}\times\frac{56}{72}\times\frac{10}{14}=\frac{13440}{15120}=\frac{8}{9}\)
c)\(\frac{32}{48}\times\frac{35}{21}\times\frac{63}{14}\times\frac{9}{30}=\frac{2}{3}\times\frac{5}{3}\times\frac{9}{2}\times\frac{3}{10}=\frac{270}{180}=\frac{3}{2}\)
d)\(7-\frac{72}{48}\times\frac{56}{60}-3=7-\frac{3}{2}\times\frac{14}{15}-3\)
\(=7-\frac{7}{5}-3\)
\(=\frac{35}{5}-\frac{7}{5}-\frac{15}{5}\)
\(=\frac{13}{5}\)
#H
(Sai thì sửa)
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
\(\frac{4+8+12+16+...+48+52+56}{9}=\frac{420}{9}=\frac{140}{3}\)
1) 1/3 x 1/2 x 3/7 = 1/6 x 3/7 = 1/14
2) 5/4 x 1/3 + 1/7 = 5/12 + 1/7 = 47/84
3) 8 x (8/9 - 2/3) = 8 x 2/9 = 16/9
4) 5/6 x 48/20 x 1/2 = 2 x 1/2 = 1
5) (2/5 + 3/4) x 8 = 23/20 x 8 = 46/5
6) 10 x (1/2 - 1/5) = 10 x 3/10 = 3
3/8 < 3/5
6/7 < 7/8
9/5 > 3/4
8/9 > 4/9
3/8 < 3/5
6/7 < 7/8
9/5 > 3/4
8/9 > 4/9 Nếu đúng thì k cho mình nhé bạn!