Log_2aa=x    then, a=(2a)^x  ......(1)

Log_3a2a=y    then,2a=(3a)^y ......(2)

Log_4a 3a=z  then, 3a=(4a)^z ......(3)

So, 

a=(2a)^x  [from (1)]

Or, a=(3a)^xy    [from(2)]

Or, a=(4a)^xyz     [from(3)]

Multiplying both sides by 4a,

4a.a=4a.(4a)^xyz  

Or,(2a)² =(4a)^{xyz + 1} 

Or,(3a)^2y =(4a)^xyz+1 

Or,(4a)^2yz =(4a)^xyz+1 

Or, 2yz = xyz+1 .proved.

Sigma bond is stronger than Pi bond because of the following reasons:

1. The extent of overlapping in Sigma bond is greater than in Pi bond.
2. The electron density in intermolecular axis is more in Sigma bond than in Pi bond.
3. There is free rotation of atom about Sigma bond but not about Pi bond.

#include<stdio.h>

#include<conio.h>

#include<string.h>

int main() {

int i, number, num1, num2=0;

char str1[50];

num1 = number;

for(i=2; i<=20; i+=2) {

printf("%d", i);

printf(", ");

}

return 0;

}

1) That old man is Aksionov.

2) The speaker is asking about the truth of digging an escape hole .

3) The speaker means the prison's wall.