1/5+1/5^2+1/5^3+1/5^4+1/5^5+......+1/5^2012<1/4
Bài 1
a, Tính P=1+1/2(1+2)+1/3(1+2+3)+1/4(1+2+3+4)+....+1/2012(1+2+3+...+2012)
b,Tìm x thỏa mãn 4^5+4^5+4^5+4^5/3^5+3^5+3^5.6^5+6^5+6^5+6^5+6^5+6^5/2^5+2^5=2^x
Kho..................wa.....................troi.....................thi......................lanh.................ret.......................ai........................tich..........................ung.....................ho........................minh.....................cho....................do....................lanh
Kho..................wa.....................troi.....................thi......................lanh.................ret.......................ai........................tich..........................ung.....................ho........................minh.....................cho....................do....................lanh
Cho S =1/5+2/52+3/53+4/54+.......+2012/52012
So sánh S với 1/3
Cho S =1/5+2/5 mu 2 +3/5mu 3 +4/5 mu 4+....+2012/5 mu 2012
So sánh S với 1/3
Tính
A=1-5^2+5^4+5^6+5^8-...+5^100
B= 1/3+(1/3)^2+(1/3)^3+...+(1/3)^2012
CMR : 1/5^2-1/5^4+1/5^6-1/5^8+.................+1/5^2014-1/5^2012 <1/26
Chứng minh S =1/5^2 -1/5^4+1/5^6-...+1/5^4n-2+...+1/5^2010-1/5^2012<1/26
tính: \(A=\frac{1}{5}-\frac{1}{5^2}+\frac{1}{5^3}-\frac{1}{5^4}+...+\frac{1}{5^{2011}}-\frac{1}{5^{2012}}\)= ?
a/48.2012+2012+2012
b/15/16:3/8.3/4
c/1234.1236-1/1233+1234x1235
B.2/tim X
a/x:36-5=12
b/22/5:x=44/5:5/2
c/8,35.x+6,65.x=45
d/3/5-x+1/3=1/4
mong các bạn giúp mik rồi mik tik cho
e) 17/5 : X = 34/5 : 4/3
f) X : 4/5= 25/8 : 5/4
g) (X x 0,25 + 2012) x 2013 = (50 + 2012) x 2013
h) (X - 1/2) x 5/3 = 7/4 - 1/
e: \(\dfrac{17}{5}:x=\dfrac{34}{5}:\dfrac{4}{3}=\dfrac{34}{5}\cdot\dfrac{3}{4}=\dfrac{102}{20}=\dfrac{51}{10}\)
\(\Leftrightarrow x=\dfrac{17}{5}:\dfrac{51}{10}=\dfrac{17}{5}\cdot\dfrac{10}{51}=\dfrac{10}{5}\cdot\dfrac{17}{51}=2\cdot\dfrac{1}{3}=\dfrac{2}{3}\)
f: \(x:\dfrac{4}{5}=\dfrac{25}{8}:\dfrac{5}{4}=\dfrac{25}{8}\cdot\dfrac{4}{5}=\dfrac{100}{40}=\dfrac{5}{2}\)
\(\Leftrightarrow x=\dfrac{5}{2}\cdot\dfrac{4}{5}=\dfrac{4}{2}=2\)
g: \(\left(0.25x+2012\right)\cdot2013=\left(50+2012\right)\cdot2013\)
\(\Leftrightarrow0.25x+2012=50+2012\)
\(\Leftrightarrow0.25x=50\)
hay x=200
h: \(\left(x-\dfrac{1}{2}\right)\cdot\dfrac{5}{3}=\dfrac{7}{4}-1=\dfrac{3}{4}\)
\(\Leftrightarrow x-\dfrac{1}{2}=\dfrac{3}{4}:\dfrac{5}{3}=\dfrac{9}{20}\)
\(\Leftrightarrow x=\dfrac{9}{20}+\dfrac{1}{2}=\dfrac{9}{20}+\dfrac{10}{20}=\dfrac{19}{20}\)