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\(A=\left(6-\frac{2}{3}+\frac{1}{2}\right)-\left(5+\frac{5}{3}-\frac{3}{2}\right)-\left(3-\frac{7}{3}+\frac{5}{2}\right)\)
\(=6-\frac{2}{3}+\frac{1}{2}-5-\frac{5}{3}+\frac{3}{2}-3+\frac{7}{3}-\frac{5}{2}\)
\(=6-5-3+\left(\frac{-2}{3}+\frac{-5}{3}+\frac{7}{3}\right)+\left(\frac{1}{2}+\frac{3}{2}-\frac{5}{2}\right)\)
\(=-2+0+\frac{-1}{2}=\frac{-5}{2}\)
= ( 1+9 ) + ( 2+8 ) + ( 3+7) + ( 4+6) + ( 5+10 )
= 10 + 10 + 10 +10 + 15
= 10 x 4 + 15
= 40 + 15
= 55 Hok Tot !
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9
= ( 1+ 9 ) + ( 2 + 8 ) + ( 3 + 7 ) + ( 4 + 6 ) + 5
= 10 + 10 + 10 + 10 + 5
= 45
a) \(\frac{-3}{16}+\frac{-7}{16}+\frac{6}{-16}\)
\(=-\frac{3}{16}+-\frac{7}{16}+\frac{-6}{16}\)
\(=\frac{\left(-3\right)+\left(-7\right)+\left(-6\right)}{16}\)
\(=\frac{-16}{16}=-1\)
b) \(\frac{2}{5}-\frac{1}{7}+\frac{7}{10}\)
\(=\frac{28}{70}-\frac{10}{70}+\frac{49}{70}\)
\(=\frac{28-10+49}{70}\)
\(=\frac{67}{70}\)
c) \(3+\frac{1}{3}-2\frac{1}{2}\)
\(=\frac{3}{1}+\frac{1}{3}-\frac{5}{2}\)
\(=\frac{18}{6}+\frac{2}{6}-\frac{15}{6}\)
\(=\frac{18+2-15}{6}\)
\(=\frac{5}{6}\)
d) \(-\frac{3}{5}-\left(-\frac{2}{15}\right)\)
\(=-\frac{3}{5}+\frac{2}{15}\)
\(=\frac{-9}{15}+\frac{2}{15}\)
\(=-\frac{7}{15}\)
\(\frac{-3}{16}\)+(\(\frac{-7}{16}\) ) +(\(\frac{6}{-16}\))
=\(\frac{-3-7-6}{16}\)
=\(\frac{-16}{16}\)= \(-1\)
\(\frac{2}{5}\)\(-\)\(\frac{1}{7}\)+\(\frac{7}{10}\)
=\(\frac{9}{35}\)+\(\frac{7}{10}\)
=\(\frac{67}{70}\)
3+ \(\frac{1}{3}\)\(-\) \(\frac{21}{2}\)
=\(\frac{18+2-63}{6}\)
=\(\frac{-43}{6}\)
\(\frac{-3}{5}\)\(-\)(\(\frac{-2}{15}\))
=\(\frac{-3}{5}\)+\(\frac{2}{15}\)
=\(\frac{-9+2}{15}\)
=\(\frac{-7}{15}\)
Bài 1: Ta chỉ cần bỏ ngoặc rồi cộng hai phân số để ra kết quả là số tự nhiên là xong
Bài 2:
A = \(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+............+\frac{1}{2003.2004}\)
A = \(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-.............-\frac{1}{2003}+\frac{1}{2003}-\frac{1}{2004}\)
A = \(1-\frac{1}{2004}\)
A = \(\frac{2004}{2004}-\frac{1}{2004}=\frac{2003}{2004}\)
Mk làm mẫu 1 bài nha
Bài 1 :
a, = (1/4+3/4) - (5/13+8/13)+2/11
= 1 - 1 + 2/11
= 2/11
Tk mk nha
\(\frac{-7}{21} +\left(1+\frac{1}{3}\right)\)
\(=\frac{-1}{3}+1+\frac{1}{3}=1\)
C1:
A = \(3\frac{5}{7}+4\frac{2}{3}\)\(-\left(2\frac{5}{7}+2\frac{1}{3}\right)\)
A = \(3\frac{5}{7}+4\frac{2}{3}\)\(-2\frac{5}{7}-2\frac{1}{3}\)
A = \(3\frac{5}{7}-2\frac{5}{7}+4\frac{2}{3}-2\frac{1}{3}\)
A = \(1+2\frac{1}{3}\)
A = \(1+\frac{7}{3}\)
A = \(\frac{10}{3}\)
C2:
A = \(3\frac{5}{7}+4\frac{2}{3}\)\(-\left(2\frac{5}{7}+2\frac{1}{3}\right)\)
A = \(\frac{26}{7}+\frac{14}{3}-\frac{19}{7}-\frac{7}{3}\)
A = \(1+\frac{14}{3}-\frac{7}{3}=\frac{10}{3}\)
C1: Ta có: \(B=8\frac{1}{9}-3\frac{2}{7}+6\frac{8}{7}-3\frac{5}{7}\)
\(=8+\frac{1}{9}-\left(3+\frac{2}{7}\right)+6+\frac{8}{7}-\left(3+\frac{5}{7}\right)\)
\(=8+\frac{1}{9}-3-\frac{2}{7}+6+1+\frac{1}{7}-3-\frac{5}{7}\)
= \(\left(8-3+6+1-3\right)+\left(\frac{1}{9}-\frac{2}{7}+\frac{1}{7}-\frac{5}{7}\right)\)
\(=9+\left(\frac{-47}{63}\right)\)
\(=\frac{520}{63}\)
C2: Đổi hỗn số ra phân số rồi tính ( cj nghĩ thế )
\(\left(6-\frac{2}{3}+\frac{1}{2}\right)-\left(5+\frac{5}{3}-\frac{3}{2}\right)-\left(3-\frac{7}{3}+\frac{5}{2}\right)\)
\(=6-\frac{2}{3}+\frac{1}{2}-5-\frac{5}{3}+\frac{3}{2}-3+\frac{7}{3}-\frac{5}{2}\)
\(=\left(6-5-3\right)+\left(-\frac{2}{3}-\frac{5}{3}+\frac{7}{3}\right)+\left(\frac{1}{2}+\frac{3}{2}-\frac{5}{2}\right)\)
\(=-2+0-\frac{1}{2}\)
\(=-\frac{4}{2}-\frac{1}{2}\)
\(=-\frac{5}{2}\)
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