Answer:
- S7 = 175
- S17 = 2465
- Sn = 1/2(n³ +n)
Step-by-step explanation:
The progression of sums is ...
1, 5, 15, 34, 65, ...
So, first differences are ...
4, 10, 19, 31
Second differences are ...
6, 9, 12, ...
Third differences are constant:
3, 3, ...
This means the expression for Sn will be a cubic expression. If dn is the first of the n-th differences, then the equation can be written as ...
Sn = S1 +(n -1)(d1 +(n -2)/2(d2 +(n -3)/3(d3)))
And this simplifies a little bit to ...
Sn = 1 +(n -1)(4 +(n -2)(n +3)/2)
In simpler form, we have ...
Sn = 1/2(n³ +n)
Then the two terms we're interested in are ...
S7 = (1/2)(7³ +7) = 175
S17 = (1/2)(17³ +17) = 2465
If they are congrunt, and it seems like the shape was rotated, so the answer is D
Answer:
Slope is -2
Step-by-step explanation:
Answer:
Step-by-step explanation:
<u>Angle 3 makes alternate interior angle pair with angle 5</u>
