\(A=\dfrac{1}{2^1}+\dfrac{1}{2^2}+...+\dfrac{1}{2^{49}}+\dfrac{1}{2^{50}}\)
\(2A=1+\dfrac{1}{2^1}+...+\dfrac{1}{2^{49}}\)
\(\Rightarrow A=2A-A=\left(1+\dfrac{1}{2^1}+...+\dfrac{1}{2^{49}}\right)-\left(\dfrac{1}{2^1}+\dfrac{1}{2^2}+...+\dfrac{1}{2^{50}}\right)\)
\(A=1-\dfrac{1}{2^{50}}< 1\)
Vậy A < 1
1.So sánh: A=\(\frac{1}{2^1}+\frac{1}{2^2}+...+\frac{1}{2^{49}}+\frac{1}{2^{50}}\) và 1:
So sánh
\(\frac{1}{101^2}+\frac{1}{102^2}+\frac{1}{103^2}+\frac{1}{104^2}+\frac{1}{105^2}và\frac{1}{2^2.3.5^2.7}\)
C=\(\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{99}}< -\frac{1}{2}\)
D=\(\left(\frac{1}{2^2}-1\right).\left(\frac{1}{3^2}-1\right).\left(\frac{1}{4^2}-1\right)...\left(\frac{1}{100^2}-1\right)< -\frac{1}{2}\)
A=\(\left[\frac{1}{100}-1^2\right].\left[\frac{1}{100}-\left(\frac{1}{2}\right)^2\right].\left[\frac{1}{100}-\left(\frac{1}{3}\right)^2\right]....\left[\frac{1}{100}-\left(\frac{1}{20}\right)^2\right]\)
Mọi người giúp em với ạ :'(
Thực hiện phép tính
a) \(\left[6.\left(-\frac{1}{3}\right)^2-3.\left(-\frac{1}{3}\right)+1\right]:\left(-\frac{1}{3}-1\right)\)
b) \(\frac{\left(\frac{2}{3}\right)^3.\left(-\frac{3}{4}\right)^2.\left(-1\right)^{2003}}{\left(\frac{2}{5}\right)^2.\left(-\frac{5}{12}\right)^3}\)
1)\(\frac{27^4.9^3}{81^2}\)
2)\(\left(\frac{1}{5^{^{ }}}\right)^{2002}.\left(-5\right)^{2000}\)
3)\(\frac{4^{11}.4^5}{2^{31}}\)
4)\(3^2.\frac{1}{243}.81^2.\frac{1}{3^2}\)
5)\(4^2.\frac{25^2}{2^3.5^2}+32.125\)
1/Tính
a)
\(\frac{2}{5}+\frac{1}{5}\times\left(\frac{3}{4}\right)\)
b)\(\frac{5}{12}\times\left(\frac{-3}{4}\right)+\frac{7}{12}\times\left(\frac{-3}{4}\right)\)
c)\(\frac{2^{15}\times9^4}{6^6\times8^3}\)
2/Tìm x biết:
a)\(\frac{5}{7}+\frac{2}{7}x=1\)
b)0,2+\(\left|x-1,3=1,5\right|\)
c)\(2^x+5=37\)
d)\(2^x+2^{x+1}=48\)
tính:
a,(2\(^{-1}\)+3\(^{-1}\)):(2\(^{-1}\)- 3\(^{-1}\))+(2\(^{-1}\).2\(^0\)):\(2^3\)
b, \(\left(\frac{-1}{3}\right)\)\(^{-1}\)- \(\left(-\frac{6}{7}\right)\)\(^0\)+\(\left(\frac{1}{2}\right)\)\(^2\):2
Bài 1: Tìm x
a) \(\left(x-2\right)^4=256\)
b) \(\frac{x^4}{256}=81\)
c) \(125\left(x+\frac{4}{5}\right)^3=729\)
e) \(7^x+2+7x=50\)
f) \(9.13^{x-1}+\frac{4}{169}.13^{x+1}=2197\)
