Question

The sum of the 8 terms of A.P. is 12,17, 22,.... is​

Answer 1

Answer:

236

Step-by-step explanation:

Refer to the formulae in the attached image and remember them.

Using the second formula for sum:

a = 12, d = 5, n = 8

S = 8/2 [2(12) + (8-1) x 5]

S = 4(24 + 35)

S = 4(59)

S = 236

Answer 2

Answer:

t1=a=12

t2=17

t3=22

d=t2-t1

d=17-12

d=5

tn=2a+(n-1)d, put n=8

t8=2(12)+(8-1)5

t8=24+7x5

t8=24+35

t8=59

Now, for sum of 8 terms

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

S8=8/2x[2(12)+(8-1)5]

S8=8/2x24+35

S8=8/2x59

S8=4x59

S8=236

hope it help you