COMEDK · Maths · 5. Sequences and Series
Find the geometric progression for which the sum of the first two terms is -4, the fifth term is four times the third term and common ratio is less than zero
- A \(-4,-8,-16,-32\).....
- B \(4,-8,16,-32\).....
- C \(-4,8,-16,32\).....
- D \(4,8,16,32\).....
Answer & Solution
Correct Answer
(B) \(4,-8,16,-32\).....
Step-by-step Solution
Detailed explanation
Let the first term of the geometric progression be \(a\) and the common ratio be \(r\). The terms are \(a, ar, ar^2, ar^3, ar^4, \dots\) The sum of the first two terms is \(a + ar = -4\), which implies \(a(1 + r) = -4\). (Equation 1) The fifth term is four times the third term,…
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