\(\frac{1}{13}+\frac{3}{13.23}+\frac{3}{23.33}+...+\frac{3}{2303.2306}\)
\(=\frac{3}{39}+\frac{3}{13.23}+\frac{3}{23.33}+...+\frac{3}{2303.2306}\)
\(=\frac{3}{13.3}+\frac{3}{13.23}+\frac{3}{23.33}+...+\frac{3}{2303.2306}\)
\(=1-\frac{1}{13}+\frac{1}{13}-\frac{1}{23}+...+\frac{1}{2303}-\frac{1}{2306}\)
\(=1-\frac{1}{2306}=\frac{2305}{2306}\)
Bài 1 Tính nhanh
A:75-6/13+3/17-3/19|275--22/13+11/17-11/19
B:1/13+3/13.23+3/23.33+3/33.43+...+3/1993.2003
C=-1/2003.2002-1/2002.2001-1/2001.2000-...-1/3.2-1/2.1
Bài 1 Tính nhanh
A:75-6/13+3/17-3/19|275--22/13+11/17-11/19
B:1/13+3/13.23+3/23.33+3/33.43+...+3/1993.2003
C=-1/2003.2002-1/2002.2001-1/2001.2000-...-1/3.2-1/2.1
D=2/3.5+7/5.12+9/4.39
Bài 1 Tính nhanh
A:75-6/13+3/17-3/19|275--22/13+11/17-11/19
B:1/13+3/13.23+3/23.33+3/33.43+...+3/1993.2003
C=-1/2003.2002-1/2002.2001-1/2001.2000-...-1/3.2-1/2.1
D=2/3.5+7/5.12+9/4.39
Bài 3 Thực hiện phép tính một cách hợp lí
N=\(\frac{1}{13}+\frac{3}{13.23}+\frac{3}{23.33}+...+\frac{3}{1993.2003}\)
tinh nhanh
N=\(\frac{1}{1.3}+\frac{3}{13.23}+\frac{3}{23.33}+...+\frac{3}{2003.2306}\)
tính nhanh:
\(\frac{1}{13}\)+\(\frac{3}{13.23}\)+\(\frac{3}{23.33}\)+...+\(\frac{3}{1993.2003}\)
Giúp mik nhoa, mik đang cần gấp lắm ^-^
tính :
a) N = ( 1/2 - 1 ) . ( 1/3 - 1 ) . ( 1/4 - 1 ) .... ( 1/2016 - 1 ) . ( 1/2017 - 1 )
b) P = ( -1/1/2 ) . ( -1/1/3 ) . ( -1/1/4 ) ... ( -1/1/2015 ) . ( 1/1/2016 )
c) Q = 1/13 + 3/13.23 + 3/23.33 + ... + 3/2013.2023
d) R = 1/2017.2016 - 1/2016.2015 - 1/2015.2014 - ... - 1/( x+1999 ).( x+2000 )
8)Tính nhanh :
a) -3/7+5/13+ -4/7
b)-5/8+3/4+ -1/5+-3/8+1/4
c)6/7.8/13+6/7.9/13+ -3/13.6/7
d)-5/7.2/11+ -5/7.9/11+1 5/7
e)11 3/13 - (2 4/7+5 3/13)
f) (1-1/2)(1-1/3)(1-1/4)(1-1/5)
Tính nhanh:
1/3 - 1/5 - 1/13 : 2/5 - 1/3 + 1/13 : 8/3 + 2/3
