Question

sequences and series!

Q:- the nth terms of the following two series are equal . find n:
(i) 5+10+20+-----
(ii) 1280+640+320+----

Answer 1

the first one is in AP and the second one is in GP so equate the nth terms of the both
nth term of ap=a+(n-1)d
a=5,d=5 nth term is 5+(n-1)5=5+5n-5
nthe term of gp = a (r^n-1)/r-1
so we get a=1280 r=1/2
nth term is (1280 (1/2)^n-1)/1/2-1
now equate the both nth terms

mark as the brainllist answer

Answer 2

Question :-

Find the nth term of the following two series .

(1) 5 + 10 + 20 ..

Here first term ( a ) = 5 ,common difference (d) = 5

hence ,

→ it's nth term = a + ( n - 1) d

→ nth term = 5 + ( n - 1) 5

→ nth term = 5n