<h3>
Answer: D) 18</h3>
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Work Shown:
Here are the variables we're working with
- a = first term
- b = last term (aka nth term)
- n = number of terms
- S = sum of the first n terms
In this case, we know that
- a = unknown (what we want to solve for)
- b = -12
- n = 14
- S = 42
We can use this formula to help find the answer
S = (n/2)*(a+b)
This formula only works for arithmetic sequences
So,
S = (n/2)*(a+b)
42 = (14/2)*(a+(-12))
42 = 7(a-12)
42/7 = a-12
6 = a-12
6+12 = a
18 = a
a = 18 is the first term of this arithmetic sequence
That's why the answer is choice D.
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Side note: your book or your teacher may use the notation but I figured it would be easier to use 'a' and b in place of and respectively.
This requires learning how to do it so if you want to know how talk to me directly
Answer:
x=-2/7
Step-by-step explanation:
Answer:
B
Step-by-step explanation:
yes, 12² + 13² = ()²
144 + 169 = 313
313 = 313