Question

Find the common difference of an AP whose first term is
5 and the sum of its first four terms is half the

sum of its next four terms.​

Answer 1

Step-by-step explanation:

find the common difference of an A.P. whose first term is 5 and the sum of first four terms is half the sum of next four terms.

Answer 2

Answer:

d=2

Step by step

According to question

a=5

S4=4/2[2×5+3d]

S4=2(10+3d)

sum of next four terms are 5th to 8th

a=t5

t5=5+4d

sum of the next four terms= 4/2(2t5+3d)

=2[2(5+4d)+3d]

=2[10+11d]

S4=1/2×sum of next four terms

2(10+3d)=1/2×2(10+11d)

20+6d=10+11d

20-10=11d-6d

10=5d

5d=10

d=2