a9418a1fe9
* fix: clean-up Project Euler 221-240 * fix: corrections from review Co-authored-by: Tom <20648924+moT01@users.noreply.github.com> Co-authored-by: Tom <20648924+moT01@users.noreply.github.com>
45 lines
795 B
Markdown
45 lines
795 B
Markdown
---
|
|
id: 5900f4571000cf542c50ff6a
|
|
title: 'Problem 235: An Arithmetic Geometric sequence'
|
|
challengeType: 5
|
|
forumTopicId: 301879
|
|
dashedName: problem-235-an-arithmetic-geometric-sequence
|
|
---
|
|
|
|
# --description--
|
|
|
|
Given is the arithmetic-geometric sequence $u(k) = (900 - 3k)r^{k - 1}$.
|
|
|
|
Let $s(n) = \sum_{k=1 \ldots n} u(k)$.
|
|
|
|
Find the value of $r$ for which $s(5000) = -600\\,000\\,000\\,000$.
|
|
|
|
Give your answer rounded to 12 places behind the decimal point.
|
|
|
|
# --hints--
|
|
|
|
`arithmeticGeometricSequence()` should return `1.002322108633`.
|
|
|
|
```js
|
|
assert.strictEqual(arithmeticGeometricSequence(), 1.002322108633);
|
|
```
|
|
|
|
# --seed--
|
|
|
|
## --seed-contents--
|
|
|
|
```js
|
|
function arithmeticGeometricSequence() {
|
|
|
|
return true;
|
|
}
|
|
|
|
arithmeticGeometricSequence();
|
|
```
|
|
|
|
# --solutions--
|
|
|
|
```js
|
|
// solution required
|
|
```
|