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\(\frac{3}{5}+\frac{5}{1}+\frac{7}{13}\)\(+\frac{2}{5}+\frac{16}{11}+\frac{19}{13}\)
= \(\left(\frac{3}{5}+\frac{2}{5}\right)\)+\(\left(\frac{7}{13}+\frac{19}{13}\right)\)+5 +\(\frac{16}{11}\)
=1+2+5+\(\frac{16}{11}\)
=...
3/5 + 5/1 + 7/13 + 2/5 +16 /11+19/13
= (3/5+2/5)+(5/1+16/11)+(7/13+19/13)
=1+21/11+28/13
bạn tự tính tiếp nhé tiếp theo dễ lắm
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1-2+3-4+...+2003
=1+(3-2)+(5-4)+...+(2003-2002)
=1+1+1+1+1+...+1(Có 1002 số hạng 1)
=1*1002=1002
Đúng đó, bạn nhớ cho mình với nha!!!
Ta có : \(A=1-2+3-4+5-6+7-8+...+2001-2002+2003\)
\(=\left(-1\right)+\left(-1\right)+\left(-1\right)+\left(-1\right)+...+\left(-1\right)+2003\)
Tổng trên có số số (-1) là : \(\frac{\left(2002-1\right):1+1}{2}=1001\)(số)
\(\Rightarrow A=\left(-1\right).1001+2003\)
\(\Rightarrow A=\left(-1001\right)+2003\)
\(\Rightarrow A=1002\)
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Ta có : ( 1 X 3 X .........X6) chia hết cho 2 ( số chẵn)
( 18 x 17 x16 x 15 ) chia hết cho 2 ( số chẴN )
SUY RA biểu thức trên = chẵn - chẵn = chẵn ( chia hết cho 2 )
ta có: 9 chia hết cho 2;3;9
=> 1 x 3 x 5 x 7 x 9 x ...x 51 x 53 x 6 chia hết cho 2;3;9
18 chia hết cho 2;3;9
=> 18 x 17 x 16 x 15 chia hết cho 2;3;9
=> ( 1 x 3 x 5 x 7 x ...x 51 x 53 x 6) - ( 18 x 17 x 16 x 15) chia hết cho 2;3;9
ta có: 5 chia hết cho 5
=> 1 x 3 x 5 x 7 x ....x 51 x 53 x 6 chia hết cho 5
15 chia hết cho 5
=> 18 x 17 x 16 x 15 chia hết cho 5
=> ( 1 x 3 x5 x 7 x ...x 51 x 53 x 6) - ( 18 x17 x 16 x15) chia hết cho 5
KL: ( 1 x 3 x 5 x7 x...x51 x 53 x 6) - ( 18 x17 x 16 x 15) chia hết cho 2;3;5;9
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\(2\frac{4}{5}\)+3:\(\frac{3}{8}\)
=14/5+3*8/3
=14/5+8
=54/5
2>
x + 6/7=1/2*3
x+6/7=3/2
x=3/2-6/7
x=21/14-12/14
x=9/14
vậy x=9/14
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a) 6:3/5-11/6 x 6/7
= 10-11/7
= 59/7
b)41/5 x 10/11+ 5 2/11
= 82/11+ 57/11
= 139/11
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Bài 1:
\(\left(\frac{9}{4}:\frac{6}{5}\right)-1=\frac{45}{24}-1=\frac{15}{8}-1=\frac{7}{8}\)
\(2+\left(\frac{1}{4}\times\frac{2}{5}\right)=2+\frac{2}{10}=2+\frac{1}{5}=\frac{11}{5}\)
Bài 2:
\(\frac{3}{5}+\frac{2}{3}=\frac{9}{15}+\frac{10}{15}=\frac{19}{15}\)
\(1-\frac{9}{11}=\frac{1}{1}-\frac{9}{11}=\frac{11}{11}-\frac{9}{11}=\frac{2}{11}\)
\(\frac{7}{9}\times\frac{3}{14}=\frac{21}{126}=\frac{3}{18}\)
\(\frac{15}{7}:\frac{5}{21}=\frac{315}{35}=9\)
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a) \(=\frac{1}{6}x\frac{5}{2}+\frac{3}{7}\)
\(=\frac{5}{12}+\frac{3}{7}\)
\(=\frac{71}{84}\)
b) \(=\frac{8}{5}-\frac{1}{2}x\frac{1}{3}\)
\(=\frac{8}{5}-\frac{1}{6}\)
\(=\frac{43}{30}\)
a, \(\frac{1}{6}:\frac{2}{5}+\frac{3}{7}\)
\(=\frac{1}{6}\cdot\frac{5}{2}+\frac{3}{7}\)
\(=\frac{5}{12}+\frac{3}{7}\)
\(=\frac{71}{84}\)
b, \(\frac{8}{5}-\frac{1}{2}\cdot\frac{1}{3}\)
\(=\frac{8}{5}-\frac{1}{6}\)
\(=\frac{43}{30}\)
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\(\frac{12}{5}+\frac{1}{5}\times6-\frac{3}{4}\)
\(=2,4+0,2\times6-0,75\)
\(=2,4+1,2-0,75\)
\(=3,6-0,75=2,85\)
\(\frac{9}{7}-\frac{1}{7}\times3+\frac{15}{14}\)
\(=\frac{9}{7}-\frac{3}{7}+\frac{15}{14}\)
\(=\frac{18}{14}-\frac{6}{14}+\frac{15}{14}\)
\(=\frac{12}{14}+\frac{15}{14}\)
\(=\frac{27}{14}\)
37/15
\(\frac{21}{3}\)x\(\frac{1}{5}\)+\(\frac{7}{3}\)=
\(\frac{7}{5}\)+\(\frac{7}{3}\)=
\(\frac{56}{15}\)
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