\(4S=4+4^2+4^3+4^4+...+4^{100}\)

\(3S=4S-S=4^{100}-1\Rightarrow3S+1=4^{100}\)

Ta có \(32^{20}=\left(2^5\right)^{20}=2^{100}\)

\(\Rightarrow4^{100}>2^{100}\Rightarrow3S+1>32^{20}\)

 A=1/2*2/4*5/6*...*9999/10000

Có 1/2<2/3;3/4<4/5;5/6<6/7;.....;9999/10000<10000/10001

-->A<2/3.4/5.6/7......10000/10001

Gọi 2/3.4/5.6/7......10000/10001 là D

Có D=2/3.4/5.6/7......10000/10001  và S<D

S.D=(1/2.3/4.5/6.....9999/10000).(2/3.4/5.6/7......10000/10001)

S.D=1/2.3/4.5/6.....9999/10000.2/3.4/5.6/7.....10000/10001

S.D=1/2.2/3.3/4.4/5.5/6.6/7.....9999/10000.10000/10001

S.D=1/10001

Vì S<D nên S.S<S.D

-->2S<1/10001

mà 1/10001<1/100

-->2S<1/100

lại có 1/100=0,01

nên 2S<0,01

-->S<0,01

sos nayf nhor neen chacws banj tuwj tinhs

4^5=1024 ; 5^4=625 -> 4^5>5^4

4^5 > 5^4

2^91=(2^13)^7=8192^7 
5^35=(5^5)^7=3125^7 
Mà 8192>3125 nên 8192^7>3125^7 
=>2^91>5^35

tick nhé bạn

2⁹¹=(2¹³)⁷=8192⁷

5³⁵=(5⁵)⁷=3125⁷

Vì 8192⁷>3125⁷ nên 2⁹¹>5³⁵

2^91=(2^13)^7=8192^7 
5^35=(5^5)^7=3125^7 
Mà 8192>3125 nên 8192^7>3125^7 
=>2^91>5^35

2^91=(2^13)^7=8192^7 
5^35=(5^5)^7=3125^7 
Mà 8192>3125 nên 8192^7>3125^7 
=>2^91>5^35

co: 2^91 = (2^13) ^7

5^35 = (5^5)^7

suy ra 2 mu 91 lon hon 5 mu 35