Question

Sum of 6 terms of an ap is zero and 4th term is 2 find the sum of 30 terms

Answer 1

Answer:

Step-by-step explanation:

S6=0

a4=2

S30=?

So, a4=a+3d

2=a+3d

(a+3d=2)*2——> 2a+6d=4

S6=0

6/2[2a+5d]=0

2a+5d=0 ————-(2)

From (1) and (2),

2a+5d=0

2a+6d=4

(-) (-) (-)

———————

-1d=-4

d=4

2a+5d=0

2a+20=0

a=-10

Now,

S30= 15[2a+29d]

= 15(-20+116)

= 15*96

=1440