(a)[4]
Find the value of $a$ from this information.
(b)[2]
Find the value of $k$ for which the $k$th term of the arithmetic progression is zero.
Mathematics 9709 · AS & A Level · Series
Series — practice question
The arithmetic progression starts with first term $a$ and has common difference $-4$. The geometric progression begins with first term $5a$ and has common ratio $-\frac{1}{4}$. Its sum to infinity is the same as the sum of the first eight terms of the arithmetic progression.