Question

What is the number of terms in the series 5,7,9,... If it's sum is 1020

Answer 1

Answer:

n = 30

Step-by-step explanation:

a=5  d=2

Sn=1020

Sn= n/2( 2a+( n-1)*d)

n/2 (2*5 (n-1) * 2) = 1020

n/2 (8+2n) = 1020

4n + n^2=1020

n^2 +4n -1020 = 0

n( n-30) + 34 ( n-30) = 0

n+34 or n-30

ignoring n=-34

n= 30

Answer 2

Step-by-step explanation:

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