C = 8/9 * 15/16 * 24/25 * 35/36 * 48/49 * 63/64
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
+
8/9*15/16*24/25*35/36*48/49*63/64*80/81*99/100
Tính: \(A=\dfrac{3}{4}.\dfrac{8}{9}.\dfrac{15}{16}.\dfrac{24}{25}.\dfrac{35}{36}.\dfrac{48}{49}.\dfrac{63}{64}\)
Tinh:
3/4 . 8/9 . 15/16 . 24/25 . 36/36 . 48/49 . 63/64
=(3.8.15.24.36.48.63)/(4.9.16.25.36.49.64)=81/140
Tính : \(\frac{3}{4}.\frac{8}{9}.\frac{15}{16}.\frac{24}{25}.\frac{35}{36}.\frac{48}{49}.\frac{63}{64}\)
mình biết đáp án là : \(\frac{9}{16}\)thôi,còn cách giải thì mình không chắc chắn nên không viết ra
\(\frac{3.2.4.3.5.4.6.5.7.6.8.7.9}{4.3.3.4.4.5.5.6.6.7.7.8.8}\)= \(\frac{9}{16}\)
Tính :
\(A=\frac{8}{9}.\frac{15}{16}.\frac{24}{25}.\frac{35}{36}.\frac{48}{49}.\frac{63}{64}\)
\(A=\frac{8}{9}.\ \frac{15}{16}.\ \frac{24}{25}.\ \frac{35}{36}.\ \frac{48}{49}.\ \frac{63}{64}\)
\(A=\frac{2.4}{3^2}.\ \frac{3.5}{4^2}.\ \frac{4.6}{5^2}.\ \frac{5.7}{6^2}.\ \frac{6.8}{7^2}.\ \frac{7.9}{8^2}\)
\(A=\frac{2.3.4^2.5^2.6^2.7^2.8.9}{3^2.4^2.5^2.6^2.7^2.8^2}\)
\(A=\frac{2.9}{3.8}\)
\(A=\frac{3}{4}\)
Tinh nhanh
8/9 . 15/16. 24/25 . 35/36 .48/ 49 . 63/ 64 .80/ 81
cac ban oi giup minh voi nhe ai dung minh tick cho nhe
\(\frac{3}{4}x\frac{8}{9}x\frac{15}{16}x\frac{24}{25}x\frac{35}{36}x\frac{48}{49}x\frac{63}{64}\)
Tính giá trị biểu thức
\(\frac{3}{4}.\frac{8}{9}.\frac{15}{16}.\frac{24}{25}...\frac{63}{64}\)
\(=\frac{1.3}{2.2}.\frac{2.4}{3.3}.\frac{3.5}{4.4}.\frac{4.6}{5.5}...\frac{7.9}{8.8}\)
\(=\frac{1.3.2.4.3.5.4.6...7.9}{2.2.3.3.4.4.5.5...8.8}\)
\(=\frac{1.9}{2.8}=\frac{9}{16}\)
\(m=\frac{3}{4}+\frac{8}{9}+\frac{15}{16}+\frac{24}{25}+\frac{35}{36}+\frac{48}{49}+\frac{63}{64}+\frac{80}{81}\)
chứng tò, 7<m<8