An identity, in mathematics, is a relation between A and B that would result to an equality of the two. It should be expressed as A = B wherein both values has some variables that would produce the same value no matter what will be the values used for the two functions. We are given the equation as follows:
a(2x+3)=9x+15+x
To determine the value of a that would make this equation an identity, we assume a value for x. We can assume a value of 1. We do as follows:
a(2 + 3) = 9 + 15 +1
5a = 25
a = 5
Therefore, the value of a would be 5.