Here, f(x)=x² -6 logx-3=0

f(2)=4-6 log2-3=-0.806

f(3)=9-6 log3-3=3.1373

f(2).f(3)=-0.806*3.1373=-2.529422 which is negative.

Hence, the root lies between 2 and 3

c₀ =(2+3)/2=2.5

f(2.5)=6.25-6 log 2.5-3=0.8623

Now

From the table,

f(2.265625)=0.001928<10^-2

Therefore, the...

zinc will react with sulphuric acid forming zinc sulphate dissolved in solution and releasing hydrogen gas.
Zn + conc. 2 H2SO4 ZnSO4 + SO2 + 2 H2O

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.

Number of beats (n) =f2- f1

= 256 - 250

= 6 beats /sec