M=1.2+2.3+3.4+......+2009.2010
3M=1.2.3+2.3.3+3.4.3+......+2009.2010.3
3M=1.2.3+2.3.(4-1)+3.4.(5-2)+......+2009.2010.(2011-2008)
3M=1.2.3+2.3.4-1.2.3+3.4.5-2.3.4+......+2009.2010.2011
2008.2009.2010
3M=2009.2010.2011
M=(2009.2010.2011):3
M=8120598990:3
M=2706866330
a= 1/1.2 +1/2.3+1/3.4+ ...+ 1/x.x+1
1/1.2+1/2.3+1/3.4+...+1/1999.2000
S = \(\dfrac{-1}{1.2}\) - \(\dfrac{1}{2.3}\) - \(\dfrac{1}{3.4}\) - .... - \(\dfrac{1}{\left(n-1\right).n}\) ( tính)
help yourself with home !!!!!!!!!!!!
Rút gọn:
\(A=\dfrac{2^{12}.3^5-4^6.9^2}{\left(2^2.3\right)^6+8^4.3^5}-\dfrac{5^{10}.7^3-25^5.49^2}{\left(125.7\right)^3+5^9.\left(14\right)^3}\)
1/2-(1/3+1/4)<x<1/48-(1/16-1/6)
Tìm x, biết
a/ (x + 1 ) (x - 2 ) <0
b/ (x - 3 ) (x - 4 ) > 0
c/\(\dfrac{1}{2}\)-(\(\dfrac{1}{3}\)+\(\dfrac{1}{4}\))<x<\(\dfrac{1}{48}\)-(\(\dfrac{1}{16}\)-\(\dfrac{1}{6}\))
`(x-9)/48+(x+6)/12=(x-3)/4`
Câu 15 A= 1/3-3/4+3/5+1/2007-1/36+1/25-2/9
Câu 16 A=1/3- 3/4- (-3/5)+ 1/64- 2/9- 1/36+ 1/15
Câu 17 A=1/2- 2/3+ 3/4- 4/5+ 5/6- 6/7- 5/6+ 4/5- 3/4+ 2/3- 1/2
A = 1/90-1/72-1/56-1/42-1/30-1/20-1/12-1/6-1/2
