E=(1+2/3).(1+2/5).(1+2/7).....(1+2/2011)
Tính:
B = 1*2+2*3+3*4+...+2011*2012
C =1*50+2*49+3*48+...+49*2+50*1
D = 4*7+7*10+10*13+...+205*208
E = (2+4+6+8+..+2014)-(3+5+7+9+...+2011)
`C=(1+2/3)(1+2/5)(1+2/7)...(1+2/2009)(1+2/2011)`
`#P.Vy`
`C=(3/3+2/3)(5/5+2/5)(7/7+2/7)...(2009/2009+2/2009)(2011/2011+2/2011)`
`C=5/3xx7/5xx9/7xx...xx2011/2009xx2013/2011`
\(C=\dfrac{5.7.9\times...\times2011.2013}{3.5.7\times...\times2009.2011}\)
`C=671`
https://olm.vn/hoi-dap/detail/105210184248.html
C=(1+2/3). (1+2/5).(1+2/7)... (1+2/2009).(1+2/2011) = ?
C=5/3×7/5×9/7×...2011/2009×2013/2011
C=5×7×9×...×2011×2013/3×5×7×...×2009×2011
C=2013/3
C=674
Nếu sai bảo mình nhé !
🤓🤓🤓🤓🤓🤓🤓🤓🤓🤓🤓🤓😸😸😸😸😸😸😸😸😸😸🐒🐒🐒🐒🐒
C= (1+2/3).(1+2/5).(1+2/7).......(1+2/2009).(1+2/2011)
C=5/3.7/5.9/7....................2011/2009.2013/2011
=5.7.9...........2011.2013/3.5.7.............2009.2011
=2013/3
=671
C=((2011x2012-1)/(2012x2010+2011))+1(2/3)x1(2/5)+(1/2/7)-(1/2/9)-(11/3)
tự làm là hạnh phúc của mỗi công dân.
Bài 1:Tính tổng :
1.D=1+3-5+7+.........+2011
2.E=2-4+6-8+..........+2006-2008+2010-2012
3.F=2-4-6+8+810-12-14+16+...................+98-200-102+104
4.H=1+2-3-4+5+6-7-8+9+10-11-12+....................-111-112+113+114
Bài 1: Tìm x, biết
a) 3/7x - 2/3x =10/21
b) 7/35 : ( x- 1/3)=2/25
c) | 2x-4 |+1=5
d) 3.| 3 - 2x | - 1=2/5
e) 3.(x-1/2)-5(x+3/5)=-x+1/5
f) (2x-1).(x+2/3)=0
g) x+4/2008+x+3/2009=x+2/2010+x+1/2011
a, \((\frac{3}{7}-\frac{2}{3})\) .x =\(\frac{10}{21}\)
\(\frac{-5}{21}\).x=\(\frac{10}{21}\)
x= -2
Mk chỉ làm 1 phần các phằn còn lại tương tự
Bài rút gọn biểu thức
a) M=|2x-3|+|x-1| với x > 1,5
b) N=|2-x|-3|x+1| với x < -1
c) P=|3x-5|+|x-2|
d) Q=|x-3|-2.|-5x|
a, \(\frac{3}{7}x-\frac{2}{3}x=\frac{10}{21}\Rightarrow\left(\frac{3}{7}-\frac{2}{3}\right)x=\frac{10}{21}\Rightarrow x=\frac{10}{21}.\left(\frac{-21}{5}\right)\Rightarrow x=-2\)
b, \(\frac{7}{35}:\left(x-\frac{1}{3}\right)=\frac{2}{25}\Rightarrow x-\frac{1}{3}=\frac{1}{5}:\frac{2}{25}\Rightarrow x=\frac{1}{10}-\frac{1}{3}=\frac{13}{30}\)
c, \(|2x-4|+1=5\)
\(\Rightarrow\orbr{\begin{cases}2x-4=4\\2x-4=-4\end{cases}}\Rightarrow\orbr{\begin{cases}x=4\\x=0\end{cases}}\)
d, \(3.|3-2x|-1=\frac{2}{5}\)
\(\Rightarrow3.|3-2x|=\frac{7}{5}\)
\(\Rightarrow\orbr{\begin{cases}3-2x=\frac{7}{15}\\3-2x=-\frac{7}{15}\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{19}{15}\\x=\frac{26}{15}\end{cases}}\)
f, \(\left(2x-1\right).\left(x+\frac{2}{3}\right)=0\)
\(\Rightarrow\hept{\begin{cases}2x-1=0\\x+\frac{2}{3}=0\end{cases}}\Rightarrow\hept{\begin{cases}x=\frac{1}{2}\\x=-\frac{2}{3}\end{cases}}\)
1. Tính
a) 6/5 + 6/35 - 6/125 - 6/2009 - 6/2011
7/5 + 7/35 + 7/125 + 7/2009 + 7/2011
b)\(\left(1-\frac{1}{2^2}\right)\left(1-\frac{1}{3^2}\right)\left(1-\frac{1}{4^2}\right)...\left(1-\frac{1}{1998^2}\right)\)
So sanh A va B
A=-1/2011-3/11^2-5/11^3-7/11^4
B=-1/2011-7/11^2-5/11^3-3/11^4