Solve the series given below: I'll mark it as brainliest.....
15,17,26,47,86,?
(a)132
(b)149
(c)169
(d)172
Answers
Given : 15 , 17 , 26 , 47 , 86 , ?
To Find : Missing number
a.149
b.132
c.144
d.169
Solution:
15
15 + 1³ + 1 = 17
15 + 2³ + 3 = 26
15 + 3³ + 5 = 47
15 + 4³ + 7 = 86
15 + 5³ + 9 = 15 + 125 + 9 = 149
Logic is
Tₙ₊₁ = T₁ + n³ + (2n - 1 ) and T₁ = 15
149 is missing number
Learn More:
20,19,23,-4,12,? find the missing number - Brainly.in
https://brainly.in/question/13202158
brainly.in/question/3383003
Answer:
149
Step-by-step explanation:
15 - 17 = 2 ----------> this 2 can be written as (1*3) - 1
17 - 26 = 9 ----------> similarly, for 9 is (4*3) - 3
26 - 47 = 21 ----------> for 21 is (9*3) - 6
47 - 86 = 39 -----------> for 39 is (16*3) - 9
The logic here is (squres of number * 3) minus the increasing values of 3 (i.e)
(1, 3,,6,9,12....) .
so for last step, it is (25*3) - 12 = 63.
then, 86 + 63 = 149.
that's it.