Asked by Watermelon

The sixth term of an Arithmetic Progression is 23 and the sum of the six terms is 78. Find the first term and the common difference.
Answered by Steve
a+5d = 23
6/2 * [a + (a+5d)] = 78

a + 5d = 23
6a + 15d = 78

a=3
d=4

sequence: 3 7 11 15 19 23
sum: 78
Answered by Watermelon
Given an arithmetic progression -7,-3,1,..., state three consecutive terms in this progression which sum up to 75.
Answered by Steve
The kth term is a+(k-1)d
so you want

3a + (k-1 + k + k+1)d = 75

3(-7) + 3k(4) = 75
12k = 96
k=8

So, the 8th,9th,10th terms are

21,25,29 add up to 75
Answered by NCaxUXvPLp
I can already tell that's gonna be super hlepufl.
Answered by rema joy
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