tinh tong A=1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90
Tinh tong: A=1-5/6+7/12-9/20+11/30-13/40+15/56-17/72+19/90
tính A=1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90
3/2 - 5/6+ 7/12- 9/20 +11/30-13/42 +15/56 - 17/72+ 19/90
\(\frac{3}{2}-\frac{5}{6}+\frac{7}{12}-\frac{9}{20}+\frac{11}{30}-\frac{13}{42}+\frac{15}{56}-\frac{17}{72}+\frac{19}{90}\)
\(=\frac{1+2}{1.2}-\frac{2+3}{2.3}+\frac{3+4}{3.4}-\frac{4+5}{4.5}+\frac{5+6}{5.6}-\frac{6+7}{6.7}+\frac{7+8}{7.8}-\frac{8+9}{8.9}+\frac{9+10}{9.10}\)
\(=1+\frac{1}{2}-\frac{1}{2}+\frac{1}{3}+\frac{1}{4}-...-\frac{1}{8}-\frac{1}{9}+\frac{1}{9}+\frac{1}{10}\)
\(=\frac{11}{10}\)
3/2-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90
\(1-\frac{5}{6}+\frac{7}{12}-\frac{9}{20}+\frac{11}{30}-\frac{13}{42}+\frac{15}{56}-\frac{17}{72}+\frac{19}{20}\)
\(=1-\frac{5}{2.3}+\frac{7}{3.4}-\frac{9}{4.5}+\frac{11}{5.6}-\frac{13}{6.7}+\frac{15}{7.8}-\frac{17}{8.9}+\frac{10}{9.10}\)
\(=1-\frac{1}{2}+\frac{1}{10}\)
\(=\frac{3}{5}\)
Tính:
1 - 5/6 + 7/12 - 9/20 + 11/30 - 13/42 + 15/56 - 17/72 + 19/90
Mình đang gõ câu hỏi thì đứa em lớp 1 bấm linh tinh. Sorry nhiều, mình đã sửa rồi
Mình muốn hỏi cách làm, còn kết quả thì bấm máy tính cũng ra
1 - 5/6 + 7/12 - 9/20 + 11/30 - 13/42 + 15/56 - 17/72 + 19/90
1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90
=1-1/2-1/3+1/3+1/4-1/4-1/5+.+1/9+1/10
=1-1/2+1/10
=1/2+1/10
=5/10+1/10
=6/10
=3/5
Tính tổng A= 1- 5/6 +7/12 - 9/20 + 11/30 - 13/42 + 15/56 - 17/72 + 19/90 - 21/110 + 23/132 - 25/156
Tính tổng :
A = 1- 5/6 + 7/12 - 9/20 + 11/30 - 13/42 + 15/56 - 17/72 + 19/90
Giúp mình nhé các bạn!