Series

Level 2

2 , 6 , 12 , 20 , 30... 2,6,12,20,30...

What is the 1 1 t h 11^{th} term in the above sequence?


The answer is 132.

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

3 solutions

Hana Wehbi
May 13, 2016

2+4=6+6=12+8=20+10=30....continuing in this manner we get 110+22=132

Chew-Seong Cheong
May 13, 2016

Let the n t h n^{th} term in the sequence be a n a_n . Then we have:

{ a n } = 2 , 6 , 12 , 30... = 1 × 2 , 2 × 3 , 3 × 4 , 4 × 5... n ( n + 1 ) . . . a n = n ( n + 1 ) a 11 = 11 × 12 = 132 \begin{aligned} \{a_n \} & =2, 6, 12, 30... \\ & = 1 \times 2, 2 \times 3, 3 \times 4, 4 \times 5... n (n+1)... \\ \implies a_n & = n(n+1) \\ a_{1 1} & = 11\times 12 =\boxed {132}\end{aligned}

Rutvik Baxi
May 13, 2016

The sequence is ( a 2 a^{2} +a) or(axa+a) i.e.-->

1x1+1 , 2x2+2 , 3x3+3, ...

so the 11th term is 11x11+11=132 .

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...