Just use your formulas that you learned for this topic.
sum of 8 terms = (8/2)(first + last)
= 4(6 + 46) = 208
#2
sum(10) = (10/2)(2a + 9d) = 60
2a + 9d = 12 **
sum(15) = (15/2)(2a + 14d) = 165
2a + 14d = 22 ***
subtract ** from ***
5d = 10
d = 2
sub into **
2a + 18 = 12
a = -3
term(18) = a + 17d = .....
find the sum of the first eight term of a linear sequence whose first term is 6 and whose last term is 46
the sum of the first ten term of a linear sequence is 60 and the sum of the first fifteen term is 165 find the 18 term of the sequence
1 answer
1 answer