Question

how many terms of an A.P 17, 15, 13, 11 must be added to get a sum of 72​

Answer 1

Answer:

n=6

Step-by-step explanation:

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

72=n/2 (34+(n-1)(-2))

(72*2)=n(34-2n+2)

(144)= 36n+3n^2

3n^2+36n-144=0

=> n^2+12n-48=0

n=+/- 6

thus n=6