16 it is as easy as multiplying
First we need to determine the type of progression in the question.That's geometric progression. Because the pattern from one sequence to the others are about multiplying.
Second, determine the ratio of the progressionr = a₂/a₁
r = a₂ ÷ a₁
r = 1/2 ÷ 2
r = 1/2 × 1/2
r = 1/4
Third, determine the formula to know the recursive rulea₂ = a × 1/4
a₂ = 1/4 × a
Fourth, determine a₁. a₁ is the first term of the progressiona₁ = 2
Final answer:Recursive rule

a₁ = 2
Sec is 1/cos so sec -120 is 1/cos -120 which is -2
<span>For more difficult cases, it may be easier to draw the graph first using the domain if possible and then determine the range graphically.See if you can find the inverse function. The domain of a function's inverse function is equal to that function's range.<span>Check to see if the function repeats.</span></span>
Y=mx+b to solve its really easy good luck