Nếu 9=63 . 8=48. 7=35. 6=24. Vậy 4=?
Quan sát bảng chia dưới đây, dùng bảng chia để tìm nhanh kết quả các phép chia:
35 : 5 = ... 63 : 9 = ... 48 : 6 = ... 56 : 8 = ...
35 : 7 = ... 63 : 7 = ... 15 : 3 = ... 24 : 4 = ...
35 : 5 = 7 63 : 9 = 7 48 : 6 = 8 56 : 8 = 7
35 : 7 = 5 63 : 7 = 9 15 : 3 = 5 24 : 4 = 6
Neu 9=63
8=48
7=35
6=24
Vay 4=?
tìm B biết B=2^2/3.3^3/8^2.4^4/15^3.5^5/24^4.6^6/35^5.7^7/48^6.8^8/63^7.9^9/80^8
Nếu: 9=63
8=48
7=35
6=24
Thì : 4=?
Nếu ai giải đúng thì coi như thông minh.
nếu các số 9=63;8=48;7=35;6=24 deu cach 4lan so ban dau nen 4=16
4/3*9/8*16/15*25/24*36/35*49/48*64/63*81/80
\(\frac{4}{3}\times\frac{9}{8}\times...\times\frac{81}{80}=\frac{2^2}{1\times3}\times\frac{3^2}{2\times4}\times...\times\frac{9^2}{8\times10}\)
\(=\frac{2\times3\times4\times...\times9}{1\times2\times3\times...\times8}\times\frac{2\times3\times4\times...\times9}{3\times4\times5\times...\times10}\\ =\frac{9}{1}\times\frac{2}{10}=\frac{9}{5}\)
4/3.9/8.16/15.25/24.36/35.49/48.64/63.81/80
=3/2.16/15.25/24.36/35.49/48.64/63.81/80
=5/3.36/35.49/48.64/63.81/80
=7/4.64/63.81/80
=9/5
+
TÍNH : E=\(\frac{2^2}{3}\times\frac{3^2}{8}\times\frac{4^2}{15}\times\frac{5^2}{24}\times\frac{6^2}{35}\times\frac{7^2}{48}\times\frac{8^2}{63}\times\frac{9^2}{80}\)
\(E=\frac{2^2}{1.3}.\frac{3^2}{2.4}.\frac{4^2}{3.5}.\frac{5^2}{4.6}...\frac{9^2}{8.10}=\frac{\left(2.3.4...9\right)^2}{1.2.\left(3.4...8\right)^2.9.10}=\frac{2^2.9^2}{1.2.9.10}=\frac{18}{10}=\frac{9}{5}\)
Tính: \(A=\dfrac{3}{4}.\dfrac{8}{9}.\dfrac{15}{16}.\dfrac{24}{25}.\dfrac{35}{36}.\dfrac{48}{49}.\dfrac{63}{64}\)
C = 8/9 * 15/16 * 24/25 * 35/36 * 48/49 * 63/64
\(m=\frac{3}{4}+\frac{8}{9}+\frac{15}{16}+\frac{24}{25}+\frac{35}{36}+\frac{48}{49}+\frac{63}{64}+\frac{80}{81}\)
chứng tò, 7<m<8