Answer:
S₁₅ = 645
Step-by-step explanation:
The sum to n terms of an arithmetic sequence is
= 
[ 2a₁ + (n - 1)d ]
where a₁ is the first term and d the common difference
Using the nth term formula 
= 5n + 3 , then
a₁ = 5(1) + 3 = 5 + 3 = 8
a₂ = 5(2) + 3 = 10 + 3 = 13 , then
d = a₂ - a₁ = 13 - 8 = 5
Thus
S₁₅ = 
[ (2 × 8) + (14 × 5) ]
= 7.5( 16 + 70)
= 7.5 × 86
= 645
Answer:
The second table of values.
Step-by-step explanation:
Let's put the x-values in the second table of values in correct number order:
x: -3, -2, -1, 0, 1
Now, let's write out the y-values in correct number order:
y: 1/4, 1, 4, 16, 64
Finally, let's rewrite the second table of values with the x-values in order and the corresponding y-values underneathe:
x: -3, -2, -1 0 1
y: 64, 16, 4, 1, 1/4
As it can be seen, as the x-values get bigger in value, the y-values get smaller exponentially, which is the definition of exponential decay.
The answer to your question is X= 11
