snnzbdb
contestada

-
-
-
-
+
d. Following is the development of a formula for the sum of n consecutive integers.
S = x + (x + 1) + (x + 2) + ... + y-2) + (y - 1) + y The sum of n integers from x to y
S = y + (y - 1) + (y - 2) + ... + (x + 2) + (x + 1) + x The same sum in reverse order
28 = (x + y) + (x + y) + (x + y) + ... + (x + y) + (x + y) + (x + y) Add the equations.
28 = n(x + y)
There are n terms of (x + y).
n(x + y)
S. "
Divide each side by 2.
Use the formula to find the sum of the numbers 101-110.
e. What kind of reasoning did you use in part (d)?