heya!!
Ques . If the first , second and last terms of AP are a , b and 2a respectively . Then its sum is
A) ab/2(b-a)
B) ab/( b-a)
C) 3ab / 2 (b-a)
D) None of these
Complete solution ✔✔✔✔✔
not just options otherwise reported ❎❎❎❎❎❎❎❎❎❎❎❎
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Answers
Answered by
12
Here,
a1 = a
a2 = b
common difference d = a2- a1 =
= b-a
let n be the number of terms in series
an = 2a = a + (n-1)d
(n-1) = a /(b-a)
n = (a/(b-a)) + 1
n= b/(b-a)
: sum = n/2 ( a1 +an)
= [b/2(b-a)] (a + 2a)
= 3ab/2(b-a)
So option c is the answer
Thanks!!!
Answered by
2
#hope it help uh.
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