Here's a pattern to consider:
1+100=101
2+99=101
3+98=101
4+97=101
5+96=101
.....
This question relates to the discovery of Gauss, a mathematician. He found out that if you split 100 from 1-50 and 51-100, you could add them from each end to get a sum of 101. As there are 50 sets of addition, then the total is 50×101=5050
So, the sum of the first 100 positive integers is 5050.
Quick note
We can use a formula to find out the sum of an arithmetic series:

Where s is the sum of the series and n is the number of terms in the series. It works for the above problem.
Answer:

Step-by-step explanation:
Circle is centred at (0, -2)
-> h = 0 & k = - 2
radius of the circle (r) = y-coordinate of the center = - 2
Equation of circle in standard form is given as:

Plugging the values of h, k and r in the above equation, we find:
![(x-0)^2 +[y-(-2)]^2 = (-2)^2](https://tex.z-dn.net/?f=%28x-0%29%5E2%20%2B%5By-%28-2%29%5D%5E2%20%3D%20%28-2%29%5E2)

This is the required equation of circle.
Answer:
Part A: He spends an average of $8.50 per day
Part B: He would save $17 per week
Step-by-step explanation: