Exponential decay formula is :
[tex] y=ab^x [/tex]
Where a≠0, b≠1 , b represent growth or decay factor (or rate) and x is any real number.
But if a radioactive isotope decays in half every year which means the decay factor or decay rate is 50% or [tex] \frac{1}{2} [/tex].
So, the formula for half decay will be:
[tex] y=a(\frac{1}{2} )^x [/tex]
Where [tex] \frac{1}{2} [/tex] represent c) The rate of isotope decreases.
