3 years ago

What is the sum of the numbers in the series? 15 + 11 + 7 + . . . + (–129)

1 answer:

3 0

Using Gauss's method
Total number of terms = [15-(-129)]/4+1=36+1=37
Add
S=15+11+7+....-125-129
S=-129-125-...+7+11+15
--------------------------------
2S=-114-114-114...(37 times)
=>
sum=S=(1/2)*(-114)*37=-2109

Using AP, T(n)=15+11+7+....-129
T(n)=19-4n => T(1)=15, T(37)=-129
S(n)=(1/2)(37)(T(1)+T(37)=(1/2)37(15-129)=2109

You might be interested in

I'm almost positive that the answer is C; no solution. But is it possible to graph that?

andrew-mc [135]

Hi again!

Yes the correct answer is C - There are no solution.

I'm not gonna solve it since you already got the right answer.

Now how do we graph?

We cannot solve this. I used different online graphing calculator but none of them graphed it.

I hope this helps again!

7 0

3 years ago

on a map, the scale shown is 1 inch : 5 miles. if an island is 2.5 square inches on the map, what is the actual are of the islan

Assoli18 [71]

Answer:

1 in^2 = 5 mi * 5 mi = 25 mi^2

2.5 in^2 (25 mi^2/in^2) = 62.5 mi^2

Step-by-step explanation:

3 0

3 years ago

Write equation and solve : I WILL GIVE BRAINLIST ///Three times a number decreased by 4 is the same as 5 times a number increase

katovenus [111]