Question

if the nth term of an ap is 9-5n find the sum of first 12 terms​

Answer 1

Answer:

An= 9-5n

a1= 9-5=4

a2= 9-10= -1

d= a2-a1= -1-4 = -5

Step-by-step explanation:

S12= n/2{2a+(n-1)d}

=12/2{2×4+(12-1)-5}

= 6{8+11× -5}

=6(8-55)

= 6× -47= -282

So the sum of first 12 terms is -282

I hope my answer will help you a lot