8/3*7+8/7*11+8/11*15+....8/107*111
tinh cac tong sau
A= 4/ 3*7+4/7*11+4/11*15 +...+4/107*111
B= 2/15 +2/35+2/63+...+2/399
C= 7/10*11+7/11*12+7/12*13+...+7/69*70
D= 6/15*18+6/18*21+6/21*24+...+6/87*90
E= 3 mu 2/ 8*11+ 3mu2/11*14+3mu2/14*17+...+3 mu2 / 197*200
\(A=\frac{4}{3.7}+\frac{4}{7.11}+...+\frac{4}{107.111}\)
\(A=\frac{1}{3}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+...+\frac{1}{107}-\frac{1}{111}\)
\(A=\frac{1}{3}-\frac{1}{111}\)
\(A=\frac{12}{37}\)
mà dài quá bạn ơi ban tách ra thành nhiều câu hỏi đi thế này trả lời lâu lắm
7/3 +7/14-7/15 phần 8/13+8/14-8/15 - 5/11-5/13+5/15 phần 8/11-8/13+8/15
GIÚP MÌNH VỚI NHA MÌNH ĐANG CẦN GẤP LẮM
\(\dfrac{\dfrac{7}{13}+\dfrac{7}{14}-\dfrac{7}{15}}{\dfrac{8}{13}+\dfrac{8}{14}-\dfrac{8}{15}}-\dfrac{\dfrac{5}{11}-\dfrac{5}{13}+\dfrac{5}{15}}{\dfrac{8}{11}-\dfrac{8}{13}+\dfrac{8}{15}}\)
\(=\dfrac{7\left(\dfrac{1}{13}+\dfrac{1}{14}-\dfrac{1}{15}\right)}{8\left(\dfrac{1}{13}+\dfrac{1}{14}-\dfrac{1}{15}\right)}-\dfrac{5\left(\dfrac{1}{11}-\dfrac{1}{13}+\dfrac{1}{15}\right)}{8\left(\dfrac{1}{11}-\dfrac{1}{13}+\dfrac{1}{15}\right)}\)
\(=\dfrac{7}{8}-\dfrac{5}{8}\)
\(=\dfrac{2}{8}=\dfrac{1}{4}\)
tham khảo nhé! Nhớ tick nhé.
https://olm.vn/hoi-dap/tim-kiem?id=1126722&subject=1&q=7%E2%80%8B%E2%80%8B+ph%E1%BA%A7n+13+x+7+ph%E1%BA%A7n+15+-+5+ph%E1%BA%A7n+12+x+21+ph%E1%BA%A7n+39+++49+ph%E1%BA%A7n+91+x+8+ph%E1%BA%A7n+15
A=11/1*2+11/2*3+11/3*4+...+11/199*200
B=14*8-16*9-18*10-...-222*112 phần 111*12+...+9/10+8*9+7*8
2 + 3/8 x 4/7 =
8/15 : 2/11 + 7/15 : 2/11 =
\(\dfrac{2}{1}+\dfrac{12}{56}=\dfrac{112+12}{56}=\dfrac{122}{56}=\dfrac{61}{28}\)
\(\left(\dfrac{8+7}{15}\right):\dfrac{2}{11}\)
\(1:\)\(\dfrac{2}{11}\)
\(\dfrac{11}{2}\)
\(\dfrac{2}{1}+\dfrac{12}{56}=\dfrac{112}{56}+\dfrac{12}{56}=\dfrac{122}{56}=\dfrac{61}{28}\)
\(=\left(\dfrac{8}{15}+\dfrac{7}{15}\right)\times\dfrac{11}{2}=\dfrac{15}{15}\times\dfrac{11}{2}=1\times\dfrac{11}{2}=\dfrac{11}{2}\)
2 + 3/8 x 4/7 =61/28
8/15 : 2/11 + 7/15 : 2/11 =11/2
1/72 nhân 7^4 nhân 11^2 nhân 77^4 nhân 1^8/7^2 nhân(7^8)^3 nhân (-11)^3 nhân 7^15 nhân 11^8
8. \(\dfrac{-5}{9}\) + \(\dfrac{8}{15}\) + \(\dfrac{-2}{11}\) + \(\dfrac{4}{-9}\) + \(\dfrac{7}{15}\)
9. \(\dfrac{2}{7}\) + (\(\dfrac{-2}{5}\) + \(\dfrac{5}{7}\))
10. \(\dfrac{7}{19}\). \(\dfrac{8}{11}\) + \(\dfrac{3}{11}\).\(\dfrac{7}{19}\)+\(\dfrac{-12}{19}\)
11. \(\dfrac{-5}{7}\).\(\dfrac{2}{11}\) + \(\dfrac{-5}{7}\).\(\dfrac{9}{11}\)
12. \(\dfrac{-5}{13}\) + \(\dfrac{5}{7}\) + \(\dfrac{20}{41}\) + \(\dfrac{-8}{13}\) + \(\dfrac{21}{41}\)
Giúp tớ với ạ! Tớ cảm ơn! Các cậu chỉ cần ghi đáp án cuối cùng thôi ạ! Cảm ơn các cậu<3
8: \(=\dfrac{-5}{9}-\dfrac{4}{9}+\dfrac{8}{15}+\dfrac{7}{15}-\dfrac{2}{11}=\dfrac{-2}{11}\)
9: =2/7-2/5+5/7=1-2/5=3/5
10: \(=\dfrac{7}{19}\left(\dfrac{8}{11}+\dfrac{3}{11}\right)-\dfrac{12}{19}=\dfrac{-5}{19}\)
11: \(=\dfrac{-5}{7}\left(\dfrac{2}{11}+\dfrac{9}{11}\right)=\dfrac{-5}{7}\)
8 = -2/11
9 = 3/5
10 = -5/19
11 = -5/7
11 = 5/13
Tính nhẩm:
18 − 9 = ..... 17 − 9 = .....
16 − 9 = ..... 15 − 6 = .....
15 − 7 = ..... 15 − 8 = .....
11 − 7 = ..... 12 − 8 = .....
13 − 9 = ..... 11 − 6 = .....
14 − 6 = ..... 11 − 3 = .....
Phương pháp giải:
Trừ nhẩm các số rồi điền kết quả vào chỗ trống.
Lời giải chi tiết:
18 − 9 = 9 17 − 9 = 8
16 − 9 = 7 15 − 6 = 9
15 − 7 = 8 15 − 8 = 7
11 − 7 = 4 12 − 8 = 4
13 − 9 = 4 11 − 6 = 5
14 − 6 = 8 11 − 3 = 8
18-9=9; 17-9=8; 16-9=7; 15-6=9; 15-7=8; 15-8=7.
{ < , >, = }
5/6......11/12 4/7.......3/4 5/8..........3/8
10/14.....5/7 10/9 .......10/11 8/15...........8/9
5/6<11/12,4/7<3/4,5/8<3/8,10/14=5/7,10/9>10/11,8/15<8/9
5/6 <11/12 4/7<3/4 5/8>3/8
10/14=5/7 10/9>10/11 8/15<8/9
Tính nhanh
a/ (5/12 + 1/8 - 7/11) / (49/11 - 7/8 - 35/12)
b/ ( 5 - 5/3 - 5/9 - 5/27) / (-8 + 8/3 + 8/9 + 8/27) : (15 - 15/11 - 15/121) / (16 - 16/11 - 16/121)