Answer:
Your friend is incorrect because if you divide 21 by 7 you will get 3 if you add 7 to 3 you get 10 therefore your friend is incorrect.
Answer:
1.
Statement: m∠A + m∠B + m∠C = <u>180°</u>
Reason: <u>Sum of Angles in a Triangle</u>
2.
Statement: 28° + x - 4° + <u>2x</u> = 180°
Reason: Substitution
3.
Statement: x = <u>52°</u>
Reason: Algebra
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
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