Step 1 :The problem is asking to simplify the expression \(\log _{5}\left(2 x^{9}\right)+\log _{5}\left(5 x^{2}\right)\) into a single logarithm with a coefficient of 1.
Step 2 :From the properties of logarithms, we know that the sum of two logarithms with the same base is equal to the logarithm of the product of the numbers.
Step 3 :So, we can simplify the expression by multiplying the numbers inside the logarithms.
Step 4 :The simplified expression is \(\boxed{\log _{5}\left(10 x^{11}\right)}\).