Which is an exponential decay function? f(x) = 3over4(7over4)^x f(x) =2over3(4over5)^–x f(x) = 3over2(8over7)^–x f(x) = 1over3(9over2)^x

In exponential decay, the value under the exponent must be less than 1 and more than 0
but wait, we have exponents that are negative values, that's interesting
it's a trick, we need to convert it to form
remember that
also that
therefor
so those ones that have the -x exponent, we need to flip the fraction

first one is 7/4, that is more than1

2nd one has a negative exponent so it becomes (3/4)(5/4)^x and 5/4 is greater than 1

3rd one has negative exponent so it becomes (3/2)(7/8)^x and 7/8 is less than 1

4th one is 9/2 and that's more than 1

3rd one is answer or is an exponential decay function