An algebra problem by sarvesh dubey

Algebra Level 3

Find the next number:
10,30,68,130,...


The answer is 222.

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4 solutions

Nihar Mahajan
Jan 30, 2015

2^3 + 2 = 10

3^3 + 3 = 30

4^3 + 4 = 68

5^3 + 5 = 130

So , next term is ,

6^3 + 6 = 222 :)

Omkar Kulkarni
Jan 30, 2015

There's this method of solving such sums, which doesn't work every time, but sometimes it does. You find the difference between consecutive terms repeatedly till the pattern is clearly visible.

10 , 30 , 68 , 130 10,30,68,130

20 , 38 , 62 \Rightarrow 20, 38, 62

18 , 24 \Rightarrow 18, 24

Here the pattern, multiples of six, is clearly visible, and we can predict the next number to be 30 30 .

Hence the answer, 30 + 62 + 130 = 222 30+62+130=\boxed{222}

FYI: This approach works only when the sequence is a polynomial. It is known as the Method of Differences .

Calvin Lin Staff - 6 years, 4 months ago

good... .......

U Z - 6 years, 4 months ago
Nuruzzaman Rakib
Jul 20, 2015

The terms of the given sequence are obtained from n+(n^3).when n =6 we get 222

Paulo Carlos
Feb 8, 2015

The diferrences between the number are, consecutively:

20 , 38 , 62... 20, 38, 62...

We note that the differences increases 18 18 then 24 24 , in other words, they are multiples of 6 6 . So, the next difference will be 30 30 times more.

Then, we have that:

130 + 62 + 30 = 222 130 + 62 + 30 = \boxed {222}

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