Math, asked by badrinath321, 1 year ago

find the sum of all two digit odd multiples of 3​


brunoconti: both solutions are wrong. resend for a solution

Answers

Answered by rslekshmi08
2

first term (a) = 15

second term = 21

third term = 27

common difference (d) =21-15 = 6

last term(t)= 99

sum = [n(a+t)]÷2

n= (t-a)÷d

= (99-15)÷6 =14

sum=[14(99+15)]÷2

= 7×114 = 798

Answered by achu220
3

ap is 15,21........99

a=15

d=21-15=6

an=99

a+(n-1)d=99

15+(n-1)6=99

(n-1)6=84

n-1=14

n=15

sn=n÷2 (a+an)

=15÷2(15+99)

=15÷2×114

=15×57

=855 is the sum

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