tính nhanh: \(1\frac{1}{4}\times1\frac{1}{8}\times1\frac{1}{15}\times1\frac{1}{24}\times1\frac{1}{35}\times...\times1\frac{1}{9800}\)
Tinh nhanh:
\(1\frac{1}{3}\times1\frac{1}{8}\times1\frac{1}{15}\times...\times1\frac{1}{9800}\)
\(1\frac{1}{3}\times\frac{1}{8}\times1\frac{1}{15}\times.....\times1\frac{1}{9800}\)
N = \(1\frac{1}{3}\times1\frac{1}{8}\times1\frac{1}{15}\times1\frac{1}{24}\times...\times1\frac{1}{99}\)
\(1\frac{1}{3}\times1\frac{1}{4}\times1\frac{1}{5}\times1\frac{1}{6}\times1\frac{1}{7}\times1\frac{1}{8}\times1\frac{1}{9}\times1\frac{1}{10}\times1\frac{1}{11}\)
\(1\frac{1}{3}.1\frac{1}{4}.1\frac{1}{5}.1\frac{1}{6}.1\frac{1}{7}.1\frac{1}{8}.1\frac{1}{9}.1\frac{1}{10}.1\frac{1}{11}\)
\(=\frac{4}{3}.\frac{5}{4}.\frac{6}{5}.\frac{7}{6}.\frac{8}{7}.\frac{9}{8}.\frac{10}{9}.\frac{11}{10}.\frac{12}{11}\)
\(=\frac{12}{3}=4\)
Tính nhanh \(1\frac{1}{15}\times1\frac{1}{16}\times1\frac{1}{17}\times...\times1\frac{1}{2009}\times1\frac{1}{2010}\)
\(=\frac{16}{15}\times\frac{17}{16}\times\frac{18}{17}\times...\times\frac{2010}{2009}\times\frac{2011}{2010}\)
\(=\frac{1}{15}\times2011\)
\(=\frac{2011}{15}\)
rút gọn biểu thức: A =\(1\frac{1}{2}\times1\frac{1}{3}\times1\frac{1}{4}\times........\times1\frac{1}{2015}\)
A=\(1\frac{1}{2}.1\frac{1}{3}.1\frac{1}{4}....1\frac{1}{2015}\)
A=\(\frac{3}{2}.\frac{4}{3}.\frac{5}{4}....\frac{2016}{2015}\)
A=\(\frac{3.4.5.....2016}{2.3.4....2015}\)
A=\(\frac{2016}{2}=1008\)
nhanh tay lên các bạn ai trả lời đầu tiên mình cho 5 cái tick
tính nhanh: \(1\frac{1}{13}\times1\frac{1}{14}\times1\frac{1}{15}\times....\times1\frac{1}{2013}\times1\frac{1}{2014}=?\)
1 1/13 x 1 1/14 x ........... x 1 1/2014 = 14/13 x 15/14 x ...... x 2015/2014 = (14 x 15 x ....x 2014) x 2015/( 14 x 15 x .......x2014) x 13 = 2015/13
Tính nhanh:
a) 12,5 x 40,7 + 59,3 x 12,5
b) 1,9 + 1,8 + 1,7 + 1,6 + 1,5 + 1,4 + 1,3 + 1,2 + 1,1
c) \(1\frac{1}{10}\times1\frac{1}{11}\times1\frac{1}{12}\times1\frac{1}{13}\times1\frac{1}{14}\times1\frac{1}{15}\times1\frac{1}{16}\)
a)
12,5 x 40,7 + 59,3 x12,5
= 12,5 x ( 40,7 + 59,3)
= 12,5 x 100
= 1250
a]
12,5 x 40,7 + 59,3 x 12,5
= 12,5 x [ 40,7 + 59,3]
= 12,5 x 100 = 125
b]
1,9 + 1,8 + 1,7 + 1,6 + 1,5 , 1,4 , 1,3 , 1,2 , 1,1
= [1,9 + 1,1 ] + [1,8 + 1,2 ] + [ 1,7 + 1,3 ] + [1,6 + 1,4 ] + 1,5
= [3 + 3 + 3 + 3 ]+ 1,5
= 12 + 1,5
=13,5
1,1 + 1,2 + 1,3 + 1,4 + 1,5 + 1,6 + 1,7 + 1,8 + 1,9
= (1,1 + 1,9) + (1,2 + 1,8) + (1,3 + 1,7) + (1,4 + 1,6) + 1,5
= 3 + 3 + 3 + 3 + 1,5
= 6 + 3 + 3 + 1,5
= 9 + 3 + 1,5
= 12 + 1,5
= 13,5
