1) -2 -6
2) -2 -y
3) -2 -6 + -y
4) -2 -6 -y
This question is incomplete, here is the complete question
What is the recursive formula for this geometric sequence 2, -10, 50, -250, .... ?
The recursive formula for this geometric sequence is:
= 2;
= (-5) • 
Step-by-step explanation:
To find the recursive formula for a geometric sequence:
- Determine if the sequence is geometric (Do you multiply, or divide, the same amount from one term to the next?)
- Find the common ratio. (The number you multiply or divide.)
- Create a recursive formula by stating the first term, and then stating the formula to be the common ratio times the previous term.
The recursive formula is:
= first term;
= r •
, where
is the first term in the sequence
is the term before the nth term - r is the common ratio
∵ The geometric sequence is 2 , -10 , 50 , -250
∴
= 2
- To find r divide the 2nd term by the first term
∵ 
∴ 
- Substitute the values of
and r in the formula above
∴
= 2;
= (-5) • 
The recursive formula for this geometric sequence is:
= 2;
= (-5) • 
Learn more:
You can learn more about the geometric sequence in brainly.com/question/1522572
#LearnwithBrainly
For this case we have the following solution.
x = gallons of water to be added
For the 10% solution we have:
0.1 * 8 = 0.8
Then, for 5% we have:
(0.8 / x + 8) = 0.05
Rewriting:
(0.8 / x + 8) = (5/100)
Answer:
An equation can be used to find x, the humber of gallons of water he should add is:
(0.8 / x + 8) = (5/100)
2^2 x 5 x 7 =140
^ is used to represent exponent