Question

sum of 'n' terms of A•P. 24,21,18, .............. is 108. Find n​

Answer 1

Answer:

this is the ans u need

plz mark as brainliest

Answer 2

Answer:

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

108=n/2(2*24+(n-1)*-3)

216=n(48-3n+3)

216=n(51-3n)

216=3n(17-n)

72=17n-n^2

n^2-17n+72

n=17+-√289-288/2

=17+-1/2

if n is positive

n=9

if n is negative

n=8