Question

Find the sum upto n terms :
12 + 14 + 24 +58 + 164 + ....​

Answer 1

Step-by-step explanation:

272 is the answer

12 + 14 =26

26+24=50

50+58=108

108+164=272

Answer 2

$\huge\bold\purple{Answer:-}$

You can do this by grouping terms and using the geometric sum formula:

2[{6+(1−1)}+{6+(3−2)}+{6+(9−3)}+{6+(27−4)}+…]

2[{6+(1−1)}+{6+(3−2)}+{6+(9−3)}+{6+(27−4)}+…]

=2[6n+(1+3+9+27+...)−(1+2+3+4+...)]

=2[6n+(1+3+9+27+...)−(1+2+3+4+...)]

=2[6n+3n−13−1−n(n+1)2]

=2[6n+3n−13−1−n(n+1)2]

=12n+3n−1−n2−n

=12n+3n−1−n2−n

=11n+3n−1−n2