Question

How many terms of the progression 3,6,9,12... must be taken at the least to have a sum of not less than 2,000

Answer 1

Answer:

Proteins can be informally divided into three main classes, which correlate with typical tertiary structures: globular proteins, fibrous proteins, and membrane proteins. Almost all globular proteins are soluble and many are enzymes.

Answer 2

Answer:

Write formula of sum of n terms for it

$\frac{n}{2} (6 + (n - 1)3) \geqslant 2000 \\3 {n}^{2} + 6n - 3n \geqslant 2000 \\ 3 {n}^{2} + 3n - 2000 \geqslant 0 \\ n = \frac{ - 3 \pm \: \sqrt{9 + 24000} }{6} \approx \frac{40 \sqrt{15} - 3}{6} \approx25.8 \\ n \geqslant 26$

So it will be 26 .

**Since we used approximation I suggest to check nearby terms 25 , 26 , 27