The first term of an arithmetic progression is ,a , and the common difference is -4.the first term of a geometric progression is ,5a, and the common ratio is -1/4. The sum to infinity of the geometric progression is equal to the sum of the first eight terms of the arithmetic progression. Find the value of ,a,.
2 answers
a = -20
AAAaannndd the bot gets it wrong yet again!
a/(1-r) = 8/2 (2a+7d)
so
5a/(1 + 1/4) = 4(2a-28)
a = 28
a/(1-r) = 8/2 (2a+7d)
so
5a/(1 + 1/4) = 4(2a-28)
a = 28
4 answers