Which one is a complex number?

What is the recursive formula for this sequence . 10,14,18,22,26

The intensity, or loudness, of a sound can be measured in decibels (db), according to the equation 0b is the intensity of a given sound and lo is the threshold of hearing intensity. what is the intensity, in decibels, [l(db)], when 1 - 10"(%)? use a calculator. round to the nearest whole number a. 15. b. 32 c. 320 d. 737

If the formula (formula in picture) were used to find the r-value of the following data, what would be the value of to three decimal places?